Clinical Celtic warmed up for the Nou Camp with what turned out to be little more than a training exercise as they outclassed a feeble St Mirren.
The Buddies contributed to their own downfall as the unmarked Gary Hooper bundled in the 15th-minute opener.
Goalkeeper Craig Samson's fumble allowed Efe Ambrose to volley in the second three minutes later.
Victor Wanyama's half-volley and a 25-yarder ended the contest by the break before Tony Watt's late header.
Celtic head for their Champions League Group G visit to Barcelona on the back of a sixth straight victory that stretches their lead in the Scottish Premier League to five points ahead of the afternoon's later fixtures.
They do so having justified manager Neil Lennon's decision to make five changes as he rested some of his squad nursing injuries and international duty fatigue.
Opposite number Danny Lennon had replaced striker Sam Parkin with defender David Barron, admitting before kick-off that his experiment of using three strikers did not work last time out against St Johnstone.
The Paisley side started confidently as they sought their fifth straight home victory, but their defence could not cope with Celtic's own three-pronged attack.
However, the Buddies could have been ahead when David van Zanten's cross pinpointed Lewis Guy and the striker's controlled volley from 12 yards forced Fraser Forster into a save at the second attempt.
Any home optimism that engendered was quickly quashed as Lassad's low cross found the almost apologetic Hooper, who looked quizzically for an offside that never came after the ball travelled the four yards towards goal off his shin.
Ambrose provided a far more spectacular celebration of his first Celtic goal with a quadruple somersault following his close-range volley into the roof of the net after Samson let a Charlie Mulgrew free-kick slip out of his grasp.
Kenny McLean was the one player impressing for the Buddies, but the Scotland Under-21 midfielder should have burst the net from 15 yards instead of firing straight at Forster after being set up by Guy.
Wanyama effectively killed off thoughts of a St Mirren fightback after 32 minutes, the midfielder volleying low through a sea of legs from just inside the penalty box from a badly-defended corner.
The Kenya midfielder bettered that six minutes later with a beautifully controlled side-foot drive from all of 25 yards into the far corner.
With Mulgrew and Ambrose having also missed gilt-edged chances, angry St Mirren boss Lennon hauled off the hesitant Barron and replaced him with winger Dougie Imrie at half time.
Kelvin Wilson came off for Celtic as a precautionary measure, with Emilio Izaguirre his replacement, after the defender picked up an injury that is not thought to threaten his participation on Tuesday.
Celtic continued to create chances, with Beram Kayal forcing a near-post block from Samson, who then turned a Joe Ledley drive wide.
St Mirren were more in possession without the SPL's joint-second-top goalscorers managing the consolation of their first goal against Celtic in six games since the 4-0 win that led to the departure of Tony Mowbray as manager in March 2010.
Steven Thompson forced a goalline block by Forster, headed wide and volleyed over, but Celtic were to have the last word when Watt headed in Izaguirre's header with six minutes remaining before Wanyama was denied a hat-trick by the crossbar.
Live Text Commentary
Full Time The referee ends the match.90:00 +2:04
Gary Hooper takes a shot. Save made by Craig Samson.90:00 +0:52
Centre by Graham Carey.90:00 +0:04
Corner taken by Charlie Mulgrew, Victor Wanyama takes a shot.89:16
Corner taken by Charlie Mulgrew, Header on goal by Victor Wanyama from inside the box goes harmlessly over the target.88:21
Free kick awarded for an unfair challenge on Joe Ledley by John McGinn. Free kick taken by Victor Wanyama.85:54
Assist on the goal came from Emilio Izaguirre.85:54 Goal scored
Goal! - Tony Watt - St Mirren 0 - 5 Celtic Tony Watt grabs a headed goal from close in. St Mirren 0-5 Celtic.85:14
Gary Hooper takes a shot. Save made by Craig Samson.83:22
Charlie Mulgrew takes the outswinging corner, clearance by John McGinn.82:57
Nicolas Fedor Miku produces a left-footed shot from the edge of the box and misses to the left of the goal.81:32
Corner taken by Charlie Mulgrew from the right by-line.81:12
Nicolas Fedor Miku takes a shot. Blocked by Lee Mair.77:55 Substitution
Substitution John McGinn comes on in place of Jim Goodwin.77:16
Steven Thompson fouled by Efe Ambrose, the ref awards a free kick. Direct free kick taken by Jim Goodwin.76:32
Jim Goodwin crosses the ball, Steven Thompson produces a volleyed right-footed shot from deep inside the penalty area which goes wide of the right-hand post.76:00
Free kick awarded for a foul by Beram Kayal on Jim Goodwin. Free kick taken by Jim Goodwin.75:01
Effort from just outside the box by Tony Watt goes over the bar.74:10 Substitution
Substitution Adam Matthews leaves the field to be replaced by Mikael Lustig.71:54
Joe Ledley fouled by Dougie Imrie, the ref awards a free kick. Emilio Izaguirre restarts play with the free kick.
The ball is crossed by Emilio Izaguirre.69:26
Steven Thompson produces a header from close range which goes wide of the left-hand post.68:51
Direct free kick taken by Jim Goodwin.68:51 Booking
Booking Victor Wanyama goes into the book for unsporting behaviour.68:44
Foul by Victor Wanyama on Dougie Imrie, free kick awarded.67:14
Steven Thompson takes a shot. Save by Fraser Forster.63:55
Dougie Imrie concedes a free kick for a foul on Beram Kayal. Free kick taken by Beram Kayal.63:38
Nicolas Fedor Miku produces a headed effort from deep inside the six-yard box which goes wide of the right-hand upright.62:59
Outswinging corner taken by Adam Matthews from the right by-line, Victor Wanyama takes a shot. Lee Mair gets a block in.62:48
Joe Ledley has an effort at goal from just inside the box that misses to the right of the goal.61:55
Gary Hooper takes a shot. Craig Samson makes a save.60:36
Tony Watt gives away a free kick for an unfair challenge on David van Zanten. David van Zanten takes the free kick.58:39
Corner taken by Graham Carey from the right by-line, Steven Thompson produces a header from inside the area that goes over the bar.56:22
Graham Carey takes a shot. Blocked by Efe Ambrose.56:22 Substitution
Substitution Lassad Nouioui goes off and Nicolas Fedor Miku comes on.56:22
Victor Wanyama gives away a free kick for an unfair challenge on Kenny McLean.56:00
Outswinging corner taken by Jim Goodwin from the right by-line, save by Fraser Forster.55:19
Dougie Imrie takes the inswinging corner, Charlie Mulgrew manages to make a clearance.54:46
Outswinging corner taken from the right by-line by Adam Matthews, Graham Carey manages to make a clearance.54:33
Joe Ledley takes a shot. Save by Craig Samson.53:50
Shot from outside the area by Kenny McLean misses to the left of the goal.52:36
Centre by Graham Carey, Efe Ambrose makes a clearance.52:14
Lassad Nouioui is flagged offside by the assistant referee. Free kick taken by Craig Samson.51:55
Beram Kayal takes a shot. Save made by Craig Samson.51:08
Steven Thompson is caught offside. Fraser Forster takes the free kick.50:33
Unfair challenge on Jim Goodwin by Joe Ledley results in a free kick. Direct free kick taken by Craig Samson.48:21
Tony Watt produces a left-footed shot from the edge of the box and misses to the left of the target.48:02
The ball is crossed by Graham Carey, save made by Fraser Forster.46:30
Unfair challenge on Graham Carey by Gary Hooper results in a free kick. Graham Carey restarts play with the free kick.45:01
The second half kicks off.45:01 Substitution
Substitution Emilio Izaguirre joins the action as a substitute, replacing Kelvin Wilson.45:01 Substitution
Substitution Dougie Imrie comes on in place of David Barron.45:00 +0:06 Half time
Half Time It is the end of the first-half.44:39
Inswinging corner taken left-footed by Charlie Mulgrew from the left by-line.44:20
Beram Kayal takes a shot. Blocked by Marc McAusland.43:29
Unfair challenge on Adam Matthews by Graham Carey results in a free kick. Adam Matthews takes the free kick.42:22
Tony Watt is caught offside. Lee Mair takes the indirect free kick.39:55
Inswinging corner taken right-footed by Adam Matthews, Efe Ambrose produces a header from deep inside the six-yard box that clears the bar.38:39
Adam Matthews challenges Graham Carey unfairly and gives away a free kick. Graham Carey takes the free kick.37:17
Assist on the goal came from Charlie Mulgrew.37:17 Goal scored
Goal! - Victor Wanyama - St Mirren 0 - 4 Celtic Victor Wanyama finds the net with a goal from just outside the box to the top right corner of the goal. St Mirren 0-4 Celtic.34:30
The ball is delivered by Charlie Mulgrew, Header from deep inside the area by Joe Ledley goes over the bar.34:30 Booking
Booking Caution for Marc McAusland.34:07
Marc McAusland challenges Tony Watt unfairly and gives away a free kick.31:50
Assist by Adam Matthews.31:50 Goal scored
Goal! - Victor Wanyama - St Mirren 0 - 3 Celtic A goal is scored by Victor Wanyama from deep inside the penalty box to the bottom left corner of the goal. St Mirren 0-3 Celtic.31:20
Corner taken right-footed by Adam Matthews,31:06
The ball is delivered by Lassad Nouioui, Paul Dummett makes a clearance.30:27
Adam Matthews sends in a cross, Lassad Nouioui has a headed effort at goal from deep inside the area missing to the left of the target.26:34
The ball is crossed by Paul Dummett.26:11
Unfair challenge on Lewis Guy by Kelvin Wilson results in a free kick. Free kick taken by David Barron.24:51
Marc McAusland challenges Tony Watt unfairly and gives away a free kick. Free kick crossed by Adam Matthews, save by Craig Samson.24:34
Kenny McLean takes a shot. Save by Fraser Forster.24:06
David Barron crosses the ball.22:21
David Barron produces a cross, clearance by Kelvin Wilson.22:03
A cross is delivered by Tony Watt, clearance by David Barron.20:10
Foul by Joe Ledley on David van Zanten, free kick awarded. David Barron restarts play with the free kick.19:23
Free kick awarded for a foul by Joe Ledley on Lewis Guy. David van Zanten restarts play with the free kick.17:40
The assist for the goal came from Charlie Mulgrew.17:40 Goal scored
Goal! - Efe Ambrose - St Mirren 0 - 2 Celtic Goal scored by Efe Ambrose from inside the six-yard box high into the middle of the goal. St Mirren 0-2 Celtic.16:53
Charlie Mulgrew sends in a cross,16:53 Booking
Booking Lee Mair receives a yellow card for unsporting behaviour.16:38
Lee Mair concedes a free kick for a foul on Tony Watt.14:28
Assist by Lassad Nouioui.14:28 Goal scored
Goal! - Gary Hooper - St Mirren 0 - 1 Celtic Gary Hooper fires in a goal from close in to the bottom left corner of the goal. St Mirren 0-1 Celtic.13:00
Joe Ledley takes a shot. Save by Craig Samson.12:27
Lewis Guy has an effort at goal. Fraser Forster makes a save.10:44
Efe Ambrose challenges Lewis Guy unfairly and gives away a free kick. Free kick taken by Jim Goodwin.9:23
Adam Matthews fouled by Paul Dummett, the ref awards a free kick. Direct free kick taken by Efe Ambrose.8:59
Foul by Jim Goodwin on Victor Wanyama, free kick awarded. Efe Ambrose takes the free kick.7:08
Inswinging corner taken from the right by-line by Charlie Mulgrew, clearance by Steven Thompson.6:25
Jim Goodwin concedes a free kick for a foul on Tony Watt. Charlie Mulgrew takes the free kick.5:02
Kenny McLean fouled by Beram Kayal, the ref awards a free kick. Paul Dummett takes the free kick.3:52
Shot from outside the penalty box by Graham Carey goes wide right of the goal.2:48
Corner taken by Charlie Mulgrew, Header by Victor Wanyama from deep inside the penalty area misses to the left of the target.2:22
The assistant referee signals for offside against Kenny McLean. Free kick taken by Fraser Forster.2:05
The ball is crossed by David Barron.0:00
The referee gets the match started.
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