Stephen Robinson's tenure as Saints boss got off to a sticky start after Hearts ended their unbeaten run in Paisley.
The Buddies gave their new manager a warm welcome as he took his first game in charge since replacing Jim Goodwin in the dugout.
But their challenge of breaking down third-placed Hearts was made a lot tougher when Connor Ronan saw red early in the first half for a heavy challenge on Beni Baningime.
