Beram Kayal's first Celtic goal was enough to beat St Johnstone at McDiarmid Park and take the Hoops five points clear of Rangers at the top of the Clydesdale Bank Premier League.
The Hoops midfielder, signed from Maccabi Haifa last summer, struck in added time in the first half to give Neil Lennon's side a deserved interval lead which they never looked like losing.
Saints survived a controversial penalty claim in the 85th minute when substitute Michael Duberry appeared to handle the ball twice in the box as he lay on the ground but referee Iain Brines surprisingly took no action.
Had the home side somehow managed to grab an equaliser no doubt more would have been made of that decision but as it was Celtic saw the game out and put pressure on to the champions who play Aberdeen at Pittodrie on Wednesday night.
Celtic boss Lennon, who returned to the dugout for the first time following a five-match touchline ban, took the acclaim of the travelling support at the end realising his side are again in the driving seat in the title race.