Semien went 1-for-5 with a three-run home run in Friday's 11-10 win over the A's.
The veteran infielder came through when it counted for the Jays, launching a walkoff blast off Sergio Romo in the ninth inning of a game in which Toronto had been trailing 8-2 heading into the eighth. His heroics also gave Semien a new career high with 34 homers on the season, eight of which have come in his last 17 games.