Buehrle (11-7) has not suffered a loss since July 20, a span of eight starts. He gave up four hits, walked one and struck out five before a shaky performance by the bull pen almost cost the Blue Jays the win.
Janssen, however, got George Kotteras on a liner to center and Alex Gordon on a grounder to second to end the game. It was the 25th save for Janssen.
Adam Lind gave Toronto the lead with a two-run single in the first and an infield hit by Ryan Goins in the fifth brought home the other run for the Blue Jays.
Ervin Santana (8-8) suffered the loss, giving up three runs on four hits in seven innings.