OAKLAND -- Right-hander Matt Shoemaker, the Toronto Blue Jays’ top starting pitcher this season, sprained his left knee during Saturday’s 10-1 victory over the Oakland A’s and will undergo an MRI to determine the injury’s extent.

“Hopefully it’s not that bad,” Blue Jays manager Charie Montoyo said, striving to remain optimistic.

Toronto right-hander Sam Gaviglio, who relieved Shoemaker and struck out five in four perfect innings, likely would replace Shoemaker in the team’s starting rotation if a fill-in becomes necessary. Gaviglio admitted that “it would be a very big loss” if Shoemaker, 3-0 with a 1.57 ERA in five starts, were to be sidelined for a prolonged period of time. Added Gaviglio, “He’s been strong every outing.”

Shoemaker blanked Oakland for three innings and appeared to make his life easier by trapping Matt Chapman off first base with a pickoff throw. But the Blue Jays couldn’t corral Chapman as quickly as they wanted to, prompting Shoemaker to join the defenders in the rundown. Shoemaker made the inning-ending tag, but as he did so, his left leg either buckled or planted itself in some loose turf.

Montoyo acknowledged that Shoemaker violated a fundamental rule by joining the rundown. “You never want to see the pitcher involved,” Montoyo said. But, he added, “[Shoemaker’s] a gamer. He got in there because he wanted to get the out.”

On came Gaviglio, who demonstrated his stamina should the team need a starter in place of Shoemaker. “That’s one of the reasons that he pitched four innings,” Montoyo said.

Gaviglio, who ranked second among Blue Jays pitchers with 24 starts last year, sounded ready to return to that role if needed. “Whatever they tell me to do, I’ll do my job,” he said after the longest relief outing of his career.