Celtic and St Johnstone have headed into half time level following a goalless first half at McDiarmid Park, despite both sides creating a string of chances in their Scottish Premiership tie.
The visitors dominated the possession in the opening 10 minutes, with Kieran Tierney getting forward on his Celtic debut, while James Forrest had a shot blocked for a corner.
Efe Ambrose nodded the ball on for Leigh Griffiths from the resulting corner, but Alan Mannus was ready to make the save on the line for St Johnstone.
Steven MacLean had a chance to open the scoring down the other end as he was left unmarked for a free header, but Jason Denayer was ready to head it clear for the visitors.
The hosts continued to look sharp as Michael O'Halloran forced a corner before having his header cleared off the line by Ambrose moments later.
The champions were on the attack again before the break, but Griffiths had a shot deflected over the crossbar, while Scott Brown saw his header cleared off the line, ensuring that the deadlock remains at the interval.
