TORONTO — When the Yankees didn’t put Isiah Kiner-Falefa in the field in the bottom of the eighth or use him to run for Giancarlo Stanton down by a run in the top of the ninth of their 10-9 loss to the Blue Jays on Sunday, it was clear there was something wrong with the shortstop.

Kiner-Falefa is dealing with tightness in his left hamstring the past couple days and Aaron Boone said he was only going to use him in an emergency situation.

He could be back in the lineup as soon as Monday at Tampa Bay.

Kiner-Falefa said he felt the tightness earlier in the series while running to first base.

“We decided it was best to take it slow,’’ Kiner-Falefa said. “That way it’s just a couple days or one day [missed].”

He said he had a similar issue in 2020 with the Rangers after the first game of the year, missed a game and then played every game the rest of the season.

On Sunday, he hoped he’d make it in at some point.

“I was trying to secretly run back here and do stuff, just because I saw Gleyber going out there,’’ Kiner-Falefa said. “I felt like I kind of let the team down in a way today, just because we couldn’t make the switches possible.”

Kyle Higashioka is trying to put his ugly start to the season at the plate behind him.

After not homering in his first 34 games of the year, the catcher has gone deep four times in his last four games.

He led off the top of the sixth with a shot to left.

“I’m just trying to see good pitches to hit and put good swings on them,’’ Higashioka said. “Lately, I’ve been able to square the ball up more.”

He called the improvement the result of “a long process since the beginning of the year.

“I had a cold streak and you lose a little confidence,’’ Higashioka said. “You start searching and have to rein yourself back in and know who you are as a hitter. For me, it’s regaining confidence.”

But the fact the homer came in a loss in which the pitching staff gave up 10 runs for the first time this season negated the impact of the hit.

“To me, keeping runs off the board is more important,’’ Higashioka said. “Today, the homer didn’t really matter.”

With the Yankees trying to tie the game in the top of the eighth, Boone sent Jose Trevino to pinch hit for Joey Gallo against left-hander Tim Mayza.

It came after Anthony Rizzo homered against Mayza and Marwin Gonzalez singled.

While Trevino has hit well since joining the Yankees this season — and Gallo’s struggles as a Yankee are well-known — it was still striking to see the move play out, given the types of offensive players they are.

But Boone said he made the switch because of how tough Mayza is on lefties.

“He’s unique,’’ Boone said of Mayza, who has held left-handed batters to an OPS of .349 this year. “He’s as tough as they get, left-on-left.”

Boone said he would have stayed with Gallo if Gonzalez hadn’t reached base because of Gallo’s power threat, but with the runner on first, went to Trevino in an effort to prolong the inning. Trevino walked to get Mayza out of the game, but Jordan Romano got DJ LeMahieu and Aaron Judge to end the threat.