TORONTO — A cruising Toronto Blue Jays rotation has hit its first bump in the road.

With Marcus Stroman, Matt Shoemaker, Aaron Sanchez, and Trent Thornton carving through the Detroit Tigers with a franchise record 24 scoreless innings to begin the season, the club got a bit of bad news Sunday morning, learning Clayton Richard’s knee issues aren’t quite behind him.

The 35-year-old’s 2018 campaign ended in late August when he underwent left knee surgery, but this time it’s a “stress reaction” in his right knee that will force Richard to miss his scheduled start Monday.

Instead, 23-year-old right-hander Sean Reid-Foley will start the series opener against the Baltimore Orioles.

Jays manager Charlie Montoyo isn’t taking any chances with Richard’s recurring knee issues, especially since it’s a problem with his landing leg, and the veteran lefty will be shut down for at least two weeks.

“It hurts when he lands, so we have to be careful with that,” Montoyo said.

Reid-Foley showed up in the clubhouse Sunday, but won’t officially be recalled until Monday.

Thornton was also informed he’ll get another rotation turn, with Montoyo saying Ryan Borucki will miss at least one more start with left elbow soreness.

That development may not have mattered after Thornton dazzled Sunday afternoon, holding the Tigers to just two hits over five innings, walking no one and striking out eight, a franchise record for a Blue Jays pitcher making his MLB debut.

He did all that with a group of 20-25 friends and family in the stands.

“That was awesome,” Thornton beamed. “It was pretty much everything I’d dreamed of ever since I was four years old. I was able to go out there and kind of show why I belong here and having my family here to witness that was really special.

“I knew they were up there, but once I step on the mound I focus on one thing and one thing only and that’s getting guys out and helping the team win. It’s definitely in the back of my mind. I know they’re there.”

Thornton’s bread-and-butter curveball was a weapon, as he used a third of the time — 24 curveballs, 75 pitches — and struck out the side in the first inning with the offering.

It’s an intriguing start for the 25-year-old right-hander with the high leg kick and the quirky delivery, acquired in exchange for infielder Aledmys Diaz from the Houston Astros over the winter.

“I want to prove to everybody that I below up here and I think I started off on a good note and I just kind of want to build off that,” Thornton said.

While base-runners have been hard to come by at times for the Blue Jays through the first four games, good starting pitching has not.

The rotation was the backbone against the Tigers, and the health of the many oft-injured arms making up that starting five will be the obvious key moving forward.

“When they're throwing up zeroes, you've got a chance to win,” first baseman Justin Smoak said. “It's great. I told (pitching coach) Pete Walker, he's probably sleeping great right now. It's good. Keep throwing up zeroes as many times as you can.”

Despite Borucki and now Richard going down, Sanchez is hopeful they can keep it rolling.

“It’s just about staying together as a unit and pushing each other to pass the baton, really,” Sanchez said.

One way they’re attempting to come together as a group is by walking together — all five of them, along with pitching coach Pete Walker — from the bullpen to the dugout after that day’s starter has finished his pre-game warmup.

Other teams have done it in the past as a way to show solidarity, and the Jays have joined the trend.

“It's something we've talked about as a staff,” Shoemaker said. “We want to support each other. We want to pump each other up, do whatever it takes to have each of us do well. It's something each of us discussed. We want to do that, we want to set that precedent. You're facing all of us, not just one of us.”​