SAN FRANCISCO -- The Giants put the finishing touches on a 5-1 homestand and clinched their third consecutive series victory with a 3-0 win over the Reds on Wednesday afternoon at Oracle Park, but the good vibes were dampened after right-hander Johnny Cueto was forced to exit in the sixth inning with lat tightness in his back. 

Cueto was cruising through 5 2/3 scoreless innings and blew a 93.5-mph fastball past Nick Castellanos for his fourth strikeout of the afternoon, but he grimaced after throwing the pitch and immediately signaled to catcher Curt Casali that he was done. Head athletic trainer Dave Groeschner and manager Gabe Kapler quickly came out to check on Cueto, who subsequently walked off the field after throwing only 68 pitches.

“He was fighting a little something in the earlier part of the game, but I don’t know exactly what part,” Casali said. “He was grinding it out. It felt like he was doing fine. He might have maybe tweaked something compensating for another part of his body. You never want to see that, especially when he’s cruising like that. Hopefully he doesn’t have to miss a start, and if he does, hopefully it’s not too, too long.” 

Cueto was due to undergo an MRI exam after the game, raising questions about how his injury will affect the Giants’ rotation plans moving forward. The 35-year-old veteran dominated in his first three starts of the year, logging a 1.80 ERA over 20 innings, and appeared on his way to rebounding from a disappointing 2020 campaign, when he recorded a career-high 5.40 ERA over 12 starts.  

Cueto showed he has plenty left in the tank by firing 8 2/3 innings of one-run ball in the Giants’ home opener Friday, and he seemed to pick up where he left off Wednesday. He outdueled Reds right-hander Tyler Mahle and held his former club to only three hits before departing with a 2-0 lead. 

“I think any time somebody has to come off the field for any injury reason, I’m always going to have some concern,” Kapler said. “In this case, Johnny’s been throwing the ball so well. We all had visions in the dugout of that being another deep-into-the-game Johnny Cueto start. He just looked outstanding and totally in control.”  

The Giants’ bullpen carried the club the rest of the way, with Caleb Baragar, Logan Webb, Tyler Rogers and Jake McGee combining for 3 1/3 scoreless innings to close out the win. Before the game, Kapler announced that Webb would move to the bullpen to open up a spot for left-hander Alex Wood in the rotation, but Webb could ultimately return to a starting role if Cueto ends up landing on the injured list.

“It’s tough to lose him from this game,” Kapler said of Cueto. “Ultimately, if he has to miss some time, those are shoes that are going to be difficult to fill. We’ll do what we always do, which is step up for each other.” 

Mahle didn’t allow a hit over his first four innings, but the Giants finally broke through in the fifth when Austin Slater drilled a double into the right-center-field gap to score Brandon Crawford from first and give San Francisco a 1-0 lead. Slater then advanced to third on a passed ball and scored from there on a chopper by Casali to bring home an insurance run for the Giants.

At 8-4, the Giants will enjoy an off-day Thursday before embarking on their second road trip of the year to Miami and Philadelphia.  

“I think it’s been really, really fun to be a part of so far,” Casali said. “Getting off to a good start in the big leagues is hard to do. I think it’s really important that we ride out this momentum that we have to create some separation and stay above .500 and have a winning ballclub. As the kids say, we’re vibing.”