The visitors broke the deadlock less than a minute into the tie when Nir Bitton played a through ball to Leigh Griffiths, leaving the striker to coolly slot the ball under Alan Mannus.

Scott Brown came close to making it two for the Scottish champions a couple of minutes later, but the captain blasted the ball wide from an Adam Matthews cutback.

Michael O'Halloran tried to get St Johnstone back on level terms before the interval, but Craig Gordon was alert in the Celtic goal to twice deny the striker.

Mannus was kept busy down the other end as Griffiths tried to add his second, while a Virgil van Dijk header was cleared off the line, and Jason Denayer headed just over.

Celtic did not need long to double their lead in the second half as Griffiths nodded the ball forward for Stefan Johansen to fire past Mannus.

Gary Mackay-Steven tried to set Brown up to put the win beyond doubt for Ronny Deila's side, but his finish was straight into the hands of Mannus.

Van Dijk attemped a volley from just inside the box as Celtic forced a corner, but the home side made the block to keep the gap at two.

St Johnstone were back in the match just a minute later as a high ball forward dropped for O'Halloran, allowing the striker to rifle the ball into the top of the net and give the home side some late hope.

Chris Millar won a free kick as the hosts pressed for the equaliser, but none of his teammates were on hand to tap in his delivery from the set piece.

Gordon came under pressure in the final minutes as St Johnstone continued to press, but he pulled off a double save to deny Brian Graham and David Mackay late on.

James McFadden almost found the back of the net in stoppage time to earn the hosts a draw, but Gordon watched his effort from outside the box and turned it wide.

The win extends Celtic's lead to six points at the top of the Scottish Premiership table, while St Johnstone sit sixth.