TORONTO -- Keaton Winn’s manager watched from the clubhouse as the rookie shined in his first Major League start.

Winn pitched like a veteran in the Giants’ 2-1 loss to the Blue Jays on Thursday night at Rogers Centre, allowing two runs in six efficient innings. But a continued lack of run support denied Winn a victory despite his quality start, and a couple of borderline strike calls also cost San Francisco manager Gabe Kapler and third baseman J.D. Davis.

The rookie’s brilliance wasn’t lost on anyone, though.

“He was lights-out,” said Kapler. “Unfortunately, I had to watch a portion of it from inside, but that gave me a different perspective of how well he was executing at the top of the zone with his fastball … and how many good splits he threw.”

Most of the heat was away from the batter’s box in the series finale.

It started with Davis’ choice words to home-plate umpire John Tumpane after his second punchout against former Mets teammate Chris Bassitt. With runners on first and second and two out, Davis took a low sinker on a 3-2 count that Tumpane called strike three to end the top of the third.

“[Bassitt] doesn’t need any help outside the zone,” said Davis. “We’ve preached, as an offense, to pass the baton to swing at pitches in the zone with runners in scoring position, and I felt like I did that. I just tried to pass the baton to [Patrick Bailey] in a big situation where we could have maybe chipped away and gotten a run.”

That was far from the first frustrating call of the night, as Davis and Kapler argued after the game that Bassitt should have been called for a couple of pitch timer violations. Instead, the Giants left runners on first and second in the first and third innings while Bassitt regrouped after a shaky start.

It was enough to get a heated reaction out of Davis, who had never been ejected from a big league game before. He threw his bat and gestured at Tumpane while vocalizing his frustration, which prompted a quick toss.

Kapler was quick to jump over the rail of the visitors’ dugout and come to the defense of his slugger. As contained as he was while pleading Davis’ case, the skipper ended up ejected as well.

“Most of our guys are all very even-keeled,” said Kapler, who has been tossed only six times in 789 games as a manager. “So when they get bent out of shape about something, I trust that it's there. … I never expect umpires to be perfect, I do expect them to have patience. And I didn't really feel like he had a whole lot of patience with J.D.”

Through the chaos, Winn kept his focus.

Winn, the Giants’ No. 13 prospect according to MLB Pipeline, held the Blue Jays to three hits and one walk with three strikeouts on 67 pitches (46 strikes). The decisive damage came on a two-run homer from Vladimir Guerrero Jr. in the sixth inning, as Winn left a splitter up in the zone that Guerrero didn’t miss.

“I was just trying to be in the zone the whole night,” said Winn. “I left a pitch up to a good hitter.”

This will still go down as a major positive for the 25-year-old right-hander, who found comfort in getting a start after coming out of the bullpen in his first three Major League appearances.

“It definitely feels different,” Winn said. “I actually wasn't as nervous today as I usually am in the ‘pen.”

Winn’s ability to throw his splitter for strikes was on full display, and his fastball reached 98.5 mph. There weren’t many strikeouts, but as the Blue Jays’ game plan to swing early in counts became apparent, Winn was able to generate some awkward swings while the defense worked behind him.

“I mean, obviously I’m not going to expect him to be that effective every time out,” said Kapler. “He's a young player, he's going to be developing. There'll be some bumps and bruises along the way, but just being able to keep us in games and give us a chance to win [is big]. Our offense isn't going to be struggling all the time.”

Regardless of questionable calls, San Francisco’s batters struck out 14 times while managing just five hits, including a 1-for-7 mark with runners in scoring position. The Giants have now lost 20 of 21 games in which they’ve scored two runs or fewer.