HOUSTON — Seattle right-hander Bryan Woo exited the Mariners’ 4-0 win over the Houston Astros because of pectoral tightness after throwing a couple of warmup pitches in the sixth inning Friday night.

Shortly after Woo started warming up on the mound for the sixth, a team trainer and coaches came out. After a brief discussion, the All-Star exited with the trainer, and Eduard Bazardo replaced him.

“He had a little pec tightness,” manager Dan Wilson said after the Mariners’ victory, which vaulted them into first place in the American League West. “He kind of gave us a heads-up and that was why Bazardo was getting loose. We will know more tomorrow. Likely an MRI, and we will get to know a little bit more tomorrow, but that’s all we know at this point.”

Woo said he “felt a little tightness” but came out to try to throw in the sixth.

“It didn’t feel like it was best for the team,” he said. “I felt like Baz was ready to go. We’ll get some stuff done [Saturday], and I’ll know more. I really don’t know much.”

Woo said he had “felt great all game,” and that the tightness happened in the fifth.

“I just felt it at the end,” he said. “I thought it was smart to not try to push it.”

Wilson said when Woo returned to the dugout after the fifth, he told the coaching staff about the issue.

“So, that’s why we were semi-prepared. He was going to give it a shot and still felt tight, so we went to Bazardo at that point,” Wilson said.

Woo cruised through five innings, yielding one hit and one walk while striking out seven in the opener of a pivotal series between the rivals, who began the night tied atop the division.

“It’s a big series, obviously, but I tried to treat it like any other game,” Woo said. “Obviously, take care of business and come out with some urgency, but don’t try to do anything more. Just do your job.”

Woo got the win, improving to 15-7. He threw 67 pitches and lowered his ERA to 2.94. Carlos Correa got the only hit off Woo, a double with one out in the fourth.

Woo has 198 strikeouts this season.

“I think you’re obviously concerned in some ways, but in other ways, Bryan’s a tough cookie,” Wilson said. “It was smart that he let us know. There was no reason to push it. We will just find out more [Saturday].”

NEW YORK — When New York Mets right-hander Kodai Senga agreed to be optioned to Triple-A earlier this month to work on his mechanics, the ideal scenario was that he would rejoin the club soon after he was eligible to return on Sept. 20. But that isn’t happening.

Senga told club officials on a call Friday that, despite being healthy, he is not ready to pitch at the major league level after surrendering four runs over 3⅔ innings for Triple-A Syracuse on Thursday. With the minor league season concluding Sunday, the plan instead is to have Senga face hitters in a simulated setting next Tuesday or Wednesday.

Mets manager Carlos Mendoza said the team is determining where that will take place because Senga is not allowed to be with the major league team while optioned.

Senga’s first start since volunteering for the demotion was encouraging: six innings, three hits, one run and eight strikeouts with no walks. But Thursday’s start represented a significant regression for the reset.

“Stuff-wise, [he] was down,” Mendoza said of Senga’s outing on Thursday. “Whether it was the velo, execution, the secondary pitches were not sharp. So that’s the report that I got. And then, watching film, you could see it. And that’s probably one of the reasons he’s asking for one more time to face hitters, just to kind of continue to work through those issues. So that’s what we saw.”

This isn’t the first time a healthy Senga, 32, has informed the Mets that he is not comfortable pitching in major league games while healthy. Last season, Senga cited mechanical problems multiple times as the reason for delaying his season debut until late July after a shoulder injury had healed. He then strained his left calf in his first start and didn’t pitch in the regular season again.

This year, Senga was one of the best pitchers in the majors until he strained his hamstring on June 12. He landed on the injured list with a 1.47 ERA in 73⅔ innings across 13 starts. The Mets had the best record in the majors. Then he missed nearly a month and returned to toss four scoreless innings on July 11. From there, Senga recorded a 6.56 ERA in 35⅔ innings across eight starts. He pitched into the sixth inning once and completed five innings three times. The Mets, coincidentally, floundered.

With the Mets no longer able to afford short, ineffective starts as they dropped in the standings, they asked Senga to go to Triple-A. All along, he has told the Mets he is healthy. The struggles continue to perplex the team.

“We’re asking the same thing,” Mendoza said when asked why Senga hasn’t returned to his early-season form. “Healthwise, he’s 100 percent fine. There’s no issues with him. He’s not favoring anything. We just haven’t been able to help him, whether it’s mechanicals or execution, whatever the case might be here. But we haven’t gotten there yet. So this is where we’re at. But physically he’s fine.”

Senga’s troubles combined with Sean Manaea‘s ineffectiveness and injuries to other starting pitchers have forced the Mets to thrust three rookies — Nolan McLean, Jonah Tong and Brandon Sproat — into the rotation in the heat of a playoff race.

McLean was called up first to make his major league debut on Aug. 16. Tong followed and then Sproat. McLean has shined in six starts, registering a 1.19 ERA with 40 strikeouts over 37⅔ innings, and is expected to start in the three-game wild-card series should the Mets reach the postseason. Tong’s and Sproat’s roles are less certain.

Senga’s status is even more unclear. Mendoza said Senga could “maybe” be in consideration to return to pitch in the Mets’ season-ending series against the Miami Marlins, but that would require multiple unknown steps. A year ago, the Mets aggressively made room for Senga in the postseason despite him not pitching in more than two months. Senga wound up opening two games and coming out of the bullpen in a third, totaling five innings over the three appearances. This year could be different.

“We gotta get there first,” Mendoza said. “We’re having those conversations, but it’s too early to tell.”

KANSAS CITY, Mo. — Salvador Perez hit a three-run homer in Kansas City’s seven-run first inning and the Royals beat the Toronto Blue Jays 20-1 on Friday night.

The Royals sent 10 batters to the plate against Max Scherzer (5-4), who exited after recording just two outs and allowing seven hits in the shortest noninjury start of his career. It was Scherzer’s shortest outing since facing just one batter while pitching for Washington on June 11, 2021, before leaving with an injury. Also, Scherzer’s seven runs conceded in the first inning are the most allowed in any inning of his career.

According to ESPN Research, Toronto’s 19-run loss ties the largest by a division leader in a September or later regular-season game, joining the previous dubious mark set by the San Diego Padres‘ 20-1 loss to the Colorado Rockies in 2005.

Following a homer by George Springer in the top of the first inning, the Royals quickly tied it in the bottom of the inning on Carter Jensen‘s leadoff double and Bobby Witt Jr.’s RBI single. Witt scored on Vinnie Pasquantino‘s double into the left-field corner to give Kansas City the lead for good.

After a walk to Maikel Garcia — and Toronto pitching coach Pete Walker’s ejection — Perez connected for his 30th home run. Michael Massey‘s two-run homer gave Kansas City a 7-1 lead. Then after Carter Jensen hit a ground-rule double — his second two-bagger of the inning — Scherzer was pulled.

Scherzer said he wasn’t overly concerned.

“We’ll deep dive and figure out what was going on, look at more advanced things,” he said. “But when I went back and looked at the location of some of the pitches, I’m actually OK with it. In that regard, you kind of flush it and move on.”

Blue Jays manager John Schneider called it “a weird outing” from a player who’s likely bound for the Hall of Fame.

“Over the course of his career you don’t see that very often from Max, barring an injury,” Schneider said. “They came out swinging and he kind of just left things in the middle.”

Batting leadoff for the first time, Jensen hit three doubles, including a two-run double in the third to go with his two against Scherzer in the first. Jensen became the first Royals player with multiple doubles in the same inning.

Jac Caglianone hit a three-run homer in the seventh as the Royals had 10 runs and 13 hits in 1⅓ innings against catcher Tyler Heineman. Infielder Isiah Kiner-Falefa got the last two outs in the eighth inning.

Pasquantino had four of Kansas City’s franchise-record 27 hits, doubling twice as the Royals collected eight extra-base hits in the first three innings.

Royals starter Michael Lorenzen (6-11) gave up a run and three hits with three walks while striking out four in 7⅔ innings for his first win since July 6.

Schneider doesn’t expect Friday’s outing to change anything about Scherzer’s future in the rotation.

“It’s a weird outing to go two-thirds of an inning and throw a lot of pitches,” he said. “But I don’t think that will affect him going forward. It won’t make his pitch count any lower. Going forward he’ll be on a normal workload and kind of normal pitch count.”

The Associated Press contributed to this report.