OAKLAND, Calif. -- Matt Shoemaker had to choke back tears after tests revealed a torn ACL in his left knee Sunday, cutting short yet another promising season for the Toronto Blue Jays' oft-injured right-hander.

Standing in the clubhouse following a 5-4 win over the Oakland Athletics on Sunday, Shoemaker's voice quivered and he paused a few times while discussing the injury. At one point he was asked if he needed time to compose himself but declined.

"You can't put words to it,'' Shoemaker said. "Extremely frustrated but at the same time I just have to stay positive. I know I'm really upset right now, I just got the news. But stay positive, keep fighting, get this thing right and be back when it's ready to go.''

Shoemaker was hurt at the end of a rundown Saturday, and Toronto announced the diagnosis and placed him on the 10-day injured list a day later. He will undergo surgery but no date has been set.

The 32-year-old is 3-0 with a 1.57 ERA in five starts after signing a $3.5 million, one-year deal with Toronto in December. He was limited to seven starts last year with the Los Angeles Angels because of a strained right forearm. In 2016, he sustained a skull fracture when he was hit in the head by a line drive, and he has had lingering forearm trouble for a while.

"He was one of the best pitchers in baseball for the first month,'' manager Charlie Montoyo said. "I feel bad for him. I feel bad for all of us, worse for him because he was doing so great.''

Shoemaker's latest injury occurred while he was chasing Oakland's Matt Chapman in the third inning. Shoemaker applied the tag and spun around to avoid contact. The injury happened as he twirled.

Shoemaker hopped around before falling to the ground as a team trainer rushed out. He was down for several moments and sat with his head in his hands before being helped to his feet and off the field.

"I was really hoping for a knee sprain,'' Shoemaker said. "I knew what I felt. It didn't feel right, but I was just hoping for a knee sprain.''

Blue Jays first baseman Justin Smoak called it a big loss for a team that just completed a 6-1 road trip.

"He's been awesome and he's pitched well so far,'' Smoak said. "It's a freaky thing. It's tough for him, tough for us.''

Before Sunday's game, Shoemaker walked slowly through the clubhouse with the aid of a single crutch. He didn't need it when talking to reporters but had a noticeable limp.

Although it's admittedly difficult, Shoemaker said the key to his recovery will be keeping an optimistic outlook.

"The biggest thing is that it's frustrating,'' Shoemaker said. "I can deal with this stuff. I know I seem pretty upset right now, which I am. But I've had bumps in the road before and I'm just going to fight through it. That's just who I am. It's just really upsetting right now."

Infielder Richard Urena was recalled from Triple-A Buffalo.