TORONTO -- A walkoff two-run homer from catcher Danny Jansen and rookie Cavan Biggio's first career grand slam pushed the Toronto Blue Jays to a 7-5 victory against the Kansas City Royals on Saturday.

Jansen hit his game-winning homer in the ninth after the Royals had tied the game in the top of the inning. Biggio's blast to left-centre field came in the fifth inning, a few minutes after Blue Jays ace Marcus Stroman departed from the game with some discomfort in his non-throwing shoulder.

The 24-year-old Biggio, the son of Baseball Hall of Famer Craig Biggio, enjoyed his big moment in his 30th career game. His Dad's first grand slam homer arrived in his 170th outing.

Kansas City starter Homer Bailey had won his last three starts and allowed only one run in 19 innings. He cruised through the first four innings against the Blues Jays, striking out five batters and six more ground-ball outs in the first 16 batters he faced.

But in the fifth inning, Bailey loaded the bases with a pair of walks and a single to second baseman Eric Sogard. Biggio hit a 2-1 pitch that had enough to clear the wall in left-centre for his sixth homer of the season.

Stroman made his 18th start for Toronto. But he departed with a left pectoral cramp after he tossed two balls to open up the fifth inning against Royals first baseman Lucas Duda.

The righty paced around the back of the mound after his first pitch of the inning and, then after another ball, summoned Toronto trainer Nikki Huffman and manager Charlie Montoyo to the mound.

Stroman had a rough start to the game. Kansas City leadoff hitter Whit Merrifield began the first with a double off the glove of diving Toronto centre fielder Randal Grichuk. Merrifield then scored on a throwing error from Stroman after Nicky Lopez's bunt.

Lopez came around to score after Duda's single to centre for a 2-0 first-inning advantage.

Blue Jays designated hitter Vladimir Guerrero Jr. made it 2-1 with a homer to left field for his sixth of the season. But the Royals were quick to regain their two-run lead when catcher Martin Maldonado hit out his ninth to right field.

The 32-year-old Puerto Rican clubbed a homer and two doubles in the series opener on Friday, and he narrowly missed another home run down the left field line in the second inning.

Maldonado crushed a shot into the fifth deck at Rogers Centre that went foul by inches and required a video review to confirm that was the case.

Kansas City made it 4-1 on a fifth-inning double from third baseman Hunter Dozier off Stroman's replacement Sam Gaviglio that scored Lopez, who had walked.

Gaviglio, Tim Mayza, David Phelps and Derek Law were solid in relief of the injured Stroman. Daniel Hudson, however, pitched a sloppy ninth with a Billy Hamilton single and walk to Merrifield to lead off the inning. Hamilton scored on Alex Gordon's sacrifice fly to left field.

The Blue Jays have started the second half of the second of the season with back-to-back wins.