Celtic have clinched the three points in Perth after a goal from James Forrest. Deep into injury time, Turner-Cook had the chance to draw the Saints level with a header, which was saved well by Joe Hart.
Tomoki Iwata burst through the middle and rather than going himself, he decided to square it to veteran Forrest. The winger took an excellent touch and slotted it away with the outside of his foot.
Celtic never got going in the first hour but then clicked into gear. Goals from Callum McGregor and Matt O’Riley gave a deserved lead against a robust opposition.
Celtic are eleven clear of Rangers, who have to games in hand, who kick off at Ibrox against St Mirren in an hour.