A Gary Hooper hat-trick against St Mirren helped move Celtic to within four points of Rangers at the top of the Scottish Premier League.
Danny Lennon's men found themselves two goals down after eight minutes.
Georgios Samaras smashed a low shot under Craig Samson, then Hooper scored his first with a tap-in.
Hooper added his second after the break with a fine turn and shot and dinked home Celtic's fourth before sub Dylan McGeouch scored a wonderful solo goal.
Celtic's early goals followed a spell of crisp passing and good movement by the visitors in the opening three minutes.
Yet, in the blink of an eye, Celtic were on their way to making it four SPL wins in a row.
Marc McAusland gifted possession to Samaras when he took a fresh-air swipe at the ball and the Celtic striker slammed a low shot from 16 yards at goal. Samson ought to have saved it but he allowed the ball to squirm over the line.
And Samaras was involved in Celtic's second.
He picked up a pass from Joe Ledley and set off on what should by now be a trademark run - if only the Greek could find consistency. He rampaged into the St Mirren box, passed to Anthony Stokes on the left and the Irishman's ball across the face of goal was turned in by a grateful Hooper.
Celtic winger James Forrest was next to trouble the Saints goal. He hit a left-foot effort from 14 yards that Samson used his legs to smother and the Scotland international followed that with a meaty thump at goal that cleared the St Mirren crossbar by a foot or so.
With the rain bucketing down, Samaras continued to test the legs and lungs of his opponents with runs from deep, yet St Mirren gradually got a handle on the game and began to enjoy more possession by simply passing and moving.
With Jim Goodwin winning challenges in midfield, the attack-minded Paul McGowan and Kenny McLean keen to get on the ball and Nigel Hasselbaink and Gary Teale making decent runs down the left and right wings respectively, St Mirren were capable of troubling Celtic.
However, the problem for Buddies boss Lennon, who signed a new deal earlier in the week, was that there was seldom any St Mirren player in a threatening position when crosses were hit into the box.
This he hoped to put right at the interval when he swapped Teale for centre-forward Steven Thompson.
But the action was all at the other end after the break. Only 15 seconds into the second period, Samson saved superbly from Hooper's close-range shot, and he was soon called upon to repel a Beram Kayal drive.
In 53 minutes Hooper made sure of the points. Stokes ripped through the Saints defence on the left wing and crossed for the little English scorer whose turn and shot were worthy of applause.
A dejected-looking McGowan drilled a shot just over the bar from 22 yards before team-mate David Barron replaced the presumably injured van Zanten.
Hooper claimed his hat-trick when, 40 yards out, he cushioned a high ball and raced at goal. He worked a one-two with Stokes and was fortunate to get the break of the ball off a Saints defender before dinking the ball over Samson.
McGeouch had been on the pitch for Forrest for eight minutes when he scored a wonderful solo goal to make it 5-0. He waltzed from deep through the red and black jerseys before despatching a low left-foot shot into the net.
St Mirren could find no way past the Celtic rearguard and left the east end of Glasgow on the end of a heavy defeat.
Celtic, though, are now putting together a real challenge for the title.
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