The champions needed extra-time and penalties to get in to the group stages of Europe’s premier club competition and manager Gordon Strachan rested Massimo Donati, Aiden McGeady and Shunsuke Nakamura for the Clydesdale Bank Premier League encounter with the Saints.

But the Parkhead side still had enough in their tank to go two points behind leaders Rangers.

First-half strikes from Scott Brown and Scott McDonald gave the champions a comfortable interval lead.

A Jan Vennegoor of Hesselink header, a Derek Riordan effort that was deflected into his own net by Saints defender Franco Miranda and a Stephen McManus goal sealed an easy win for the Parkhead side with Miranda scoring a consolation for the home side.

With 12 minutes of an ordinary beginning to the match gone, Celtic manager Gordon Strachan became involved with fourth official Dougie McDonald after some objects appeared to fall from the Celtic physio’s bag as he ran on to treat Lee Naylor.

In a bizarre incident, the Hoops’ boss ran on to remove the objects and then, after being spoken to by McDonald for encroaching, Strachan ran back on the pitch and dumped them back on the grass.

McDonald was then forced to remove the articles during the next break in play, the pettiness of the whole situation causing a distraction from a run-of-the-mill match.

But interest returned to the game in the 21st minute when the visitors took the lead with their first real attempt on goal.

The energetic McDonald did well to play Brown in at the edge of the St Mirren penalty area and the former Hibernian player simply nudged the ball under the diving Buddies’ keeper Chris Smith from 10 yards out.

Four minutes later the Hoops doubled their lead and, with still more than an hour to play the game, looked to be over.

Mark Wilson’s long ball down the right channel, hit more in hope than expectation, caused hesitation in the Paisley side’s defence allowing McDonald to lob the ball from wide over the stranded Smith and into the net.

Without moving out of second gear, Celtic found themselves two goals to the good.

St Mirren tried to up their work-rate but the champions were organised and far too clever to succumb to a succession of crosses into their box.

However, Saints had a great chance to pull a goal back in the 40th minute when Miranda’s whipped-in cross from the left found Mark Corcoran alone at the back post.

But for some reason known only to the Love Street midfielder, he chested the ball towards goal when it was crying out to be headed.

Donati replaced the pedestrian Sno at the break as Strachan tried to inject some more life into his midfield.

After less than a minute of the restart, McDonald played a one-two with Vennegoor of Hesselink then sent a shot from distance sailing over the bar, Riordan emulating that feat moments later.

But the match was soon to be settled in Celtic’s favour.

In the 53rd minute, Riordan’s in-swinging corner from the left was met at the near post by Vennegoor of Hesselink who bulleted the ball in from around three yards out.

St Mirren boss Gus MacPherson replaced Kean with Billy Mehmet immediately afterwards, the substitution met with boos from the home fans.

Three minutes later Riordan took a Vennegoor of Hesselink pass and his shot from the right-hand side of the penalty box took a deflection off Miranda before making its way past Smith.

In the 74th minute Hoops skipper McManus made it five when he pounced six yards from goal to re-direct Riordan’s shot in to the net.

Sixty seconds later Miranda made up for his earlier mishap when he thundered a 30-yard drive past the helpless Boruc.

There was no danger of a comeback but with 10 minutes remaining the Celtic keeper made a good save from Corcoran’s angled drive.

Miranda escaped a sending-off with five minutes to go when he received only a yellow card for a blatant push on Brown’s face after the Celtic midfielder had tormented him with the ball in the corner.