Rachubka was publicly backed by boss Grayson after a mistake handed Coventry a 1-1 draw at Elland Road.
But his shaky form has continued and his manager was in less conciliatory mood on Tuesday, handing 18-year-old Alex Cairns his professional debut at the start of the second half.
Rachubka's problems began in the 13th minute when he could only parry Shelvey's shot into the path of Lua Lua, who knocked in a simple chance.
The keeper then dropped a routine catch, leading to Lees's dismissal for handling Ludovic Sylvestre's goalbound shot - Shelvey's resultant spot-kick was ordered to be retaken for encroachment but the on-loan Liverpool playmaker calmly stroked his second into the bottom corner.
Shelvey's second goal was also a gift as Rachubka dropped a speculative 25-yard Lua Lua shot at his feet as Blackpool opened a 3-0 lead inside the first 30 minutes.
Rachubka was booed as he received a backpass 10 minutes before half-time and Grayson replaced the keeper with Cairns at the interval.
Cairns, who has come through the Leeds academy, kept one Shelvey effort out but could do nothing to stop Lua Lua scoring his second when he cut inside Paul Connelly and fired into the top corner.
And Shelvey made an uncomfortable night for Grayson, against the club he left in acrimonious circumstances in December 2008, even worse when he completed his hat-trick after being played through by Martinez Angel with 12 minutes remaining.
Full Time The referee blows for the end of the match.
Ludovic Sylvestre takes a shot. Paul Connolly gets a block in.
Daniel Bogdanovic gives away a free kick for an unfair challenge on Patrick Kisnorbo. Free kick taken by Patrick Kisnorbo.
Effort from the edge of the box by Daniel Bogdanovic goes wide of the right-hand upright.
Martinez Angel takes a shot. Paul Connolly makes a save.
Short corner taken by Daniel Bogdanovic.
Assist by Martinez Angel.
77:32 Goal scored
Goal! - Jonjo Shelvey - Leeds 0 - 5 Blackpool Jonjo Shelvey finds the net with a goal from inside the penalty area to the bottom right corner of the goal. Leeds 0-5 Blackpool.
Substitution Callum McManaman leaves the field to be replaced by Thomas Ince.
Substitution Daniel Bogdanovic comes on in place of Lomana Tresor LuaLua.
Jonjo Shelvey takes a shot. Paul Connolly makes a save.
Substitution (Blackpool) makes a substitution, with Martinez Angel coming on for Keith Southern.
Substitution Mika Vayrynen on for Adam Clayton.
Corner taken by Ludovic Sylvestre from the right by-line.
Assist on the goal came from Barry Ferguson.
64:12 Goal scored
Goal! - Lomana Tresor LuaLua - Leeds 0 - 4 Blackpool Lomana Tresor LuaLua fires in a goal from inside the penalty area to the top right corner of the goal. Leeds 0-4 Blackpool.
Lomana Tresor LuaLua takes a shot from just inside the penalty box which clears the bar.
Booking Paul Connolly is booked.
Robert Snodgrass fouled by Barry Ferguson, the ref awards a free kick. Free kick taken by Robert Snodgrass.
Outswinging corner taken right-footed by Ludovic Sylvestre from the right by-line, Ian Evatt produces a header from inside the area that goes over the bar.
Jonjo Shelvey has an effort direct from the free kick.
Substitution Alex Cairns joins the action as a substitute, replacing Paul Rachubka.
Luciano Becchio is ruled offside.
Outswinging corner taken right-footed by Robert Snodgrass, clearance by Ian Evatt.
Free kick awarded for a foul by Keith Southern on Aidan White. Direct free kick taken by Paul Rachubka.
Free kick awarded for an unfair challenge on Jonjo Shelvey by Aidan White. The free kick is swung in right-footed by Ludovic Sylvestre.
Aidan White concedes a free kick for a foul on Alex Baptiste. Alex Baptiste takes the free kick.
Jonathan Howson has an effort at goal from the edge of the box that misses to the right of the target.
Short corner taken by Jonathan Howson.
Aidan White takes a shot. Matthew Gilks makes a save.
Corner from the right by-line taken by Robert Snodgrass, Barry Ferguson manages to make a clearance.
Shot from just outside the penalty area by Danny Pugh misses to the left of the target.
The referee blows for offside. Free kick taken by Matthew Gilks.
Lomana Tresor LuaLua is adjudged to have handled the ball. Free kick taken by Patrick Kisnorbo.
The referee starts the second half.
Substitution Luciano Becchio comes on in place of Andrew Keogh.
45:00 +3:22 Half time
Half Time It is the end of the first-half.
Free kick awarded for an unfair challenge on Jonjo Shelvey by Patrick Kisnorbo. Strike on goal comes in from Jonjo Shelvey from the free kick.
Ross McCormack produces a right-footed shot from deep inside the penalty area which goes wide of the right-hand post.
The official flags Andrew Keogh offside. Alex Baptiste restarts play with the free kick.
Foul by Keith Southern on Patrick Kisnorbo, free kick awarded. Paul Rachubka takes the free kick.
Assist by Lomana Tresor LuaLua.
30:37 Goal scored
Goal! - Jonjo Shelvey - Leeds 0 - 3 Blackpool Jonjo Shelvey finds the back of the net with a goal from close range low into the middle of the goal. Leeds 0-3 Blackpool.
Lomana Tresor LuaLua takes a shot. Save by Paul Rachubka.
26:03 Goal scored
Goal! - Jonjo Shelvey - Leeds 0 - 2 Blackpool Penalty taken right-footed by Jonjo Shelvey and scored. Leeds 0-2 Blackpool.
Dismissal Tom Lees is sent off by the referee.
Handball by Tom Lees.
Free kick awarded for a foul by Jonathan Howson on Lomana Tresor LuaLua. Direct free kick taken by Jonjo Shelvey.
Lomana Tresor LuaLua challenges Aidan White unfairly and gives away a free kick. Paul Rachubka takes the direct free kick.
The free kick is delivered right-footed by Robert Snodgrass from right channel, Keith Southern manages to make a clearance.
Booking The referee shows Ian Evatt a yellow card for unsporting behaviour.
Unfair challenge on Ross McCormack by Ian Evatt results in a free kick.
The assistant referee signals for offside against Andrew Keogh. Matthew Gilks restarts play with the free kick.
The offside flag is raised against Robert Snodgrass. Matthew Gilks takes the free kick.
The referee blows for offside. Paul Rachubka restarts play with the free kick.
Tom Lees sends in a cross, save by Matthew Gilks.
Robert Snodgrass delivers the ball, clearance by Alex Baptiste.
12:34 Goal scored
Goal! - Lomana Tresor LuaLua - Leeds 0 - 1 Blackpool Lomana Tresor LuaLua grabs a goal from close range to the bottom left corner of the goal. Leeds 0-1 Blackpool.
Jonjo Shelvey takes a shot. Paul Rachubka makes a save.
Unfair challenge on Adam Clayton by Keith Southern results in a free kick. Free kick crossed by Robert Snodgrass, Alex Baptiste manages to make a clearance.
Free kick awarded for a foul by Stephen Crainey on Robert Snodgrass. Free kick crossed left-footed by Robert Snodgrass, Matthew Gilks makes a save. Patrick Kisnorbo takes a shot. Save made by Matthew Gilks.
Alex Baptiste fouled by Adam Clayton, the ref awards a free kick. Matthew Gilks restarts play with the free kick.
Shot by Callum McManaman from just outside the area goes over the net.
Short corner taken by Ludovic Sylvestre from the right by-line.
The assistant referee flags for offside against Andrew Keogh. Matthew Gilks restarts play with the free kick.
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