SAN FRANCISCO -- Alex Cobb endured a disastrous return from the injured list on Sunday afternoon at Oracle Park. 

Cobb couldn’t get out of the first inning in the Giants’ 11-5 loss to the Nationals, giving up five runs (one earned) on four hits and three walks while recording only two outs in the shortest start of his 11-year career. 

The Nationals forced Cobb to throw 40 pitches and sent 11 batters to the plate in the first inning, expediting the 34-year-old right-hander’s exit in his first start since suffering a Grade 1 right adductor strain against the Mets on April 19. 

“There were a lot of poor pitches that I threw that inning,” Cobb said. “It seemed to be kind of a combination of bad luck, really bad pitches and not just executing that one pitch to get out of the inning. There were plenty of opportunities to just make one pitch and not let that unravel the way it did, and I just couldn’t do it.” 

Cobb, who missed 12 games before being activated on Sunday, was tested from the start, yielding back-to-back singles to César Hernández and Juan Soto that put a pair of runners on for Nelson Cruz.  

Cruz bounced a potential double-play ball to the left side, but the ball skipped under the glove of third baseman Jason Vosler, who was charged with an error. Hernández scored from second on the play, with Soto and Cruz each moving into scoring position. Cobb retired Josh Bell on a groundout for the first out of the inning, but Yadiel Hernandez followed with a two-run single up the middle that extended the Nationals’ lead to 3-0.

“He deserved better,” manager Gabe Kapler said of Cobb. “He came out with really good stuff and started by filling up the strike zone. … We also have to catch the ball and convert ground balls into outs. We weren’t able to do that as much as we needed to today to protect both Cobb and other pitchers. I don’t think that’s any secret. We have to play really good defense behind pitchers who get us ground balls. It’s that simple.”

Maikel Franco skied a fly ball to left field for the second out, but the situation continued to unravel after that, with Cobb issuing back-to-back walks to load the bases for former Giants prospect Lucius Fox. The Nationals tacked on two more runs after Cobb was called for a balk and Fox delivered his first career Major League hit, an infield single that beat the shift.

Hernández then worked a nine-pitch walk in his second plate appearance of the inning to load the bases and force Cobb from the game with the Giants trailing, 5-0. Left-hander Sam Long was summoned to face Soto, who struck out to end the inning.

“Physically, I felt fine,” Cobb said. “I fatigued pretty quickly halfway through the inning. I thought I was hitting all my checkpoints of driving the ball to a certain location, and it just wouldn’t go there. I ended up walking those three guys. In hindsight, I should have just let them put the ball in play and stop trying to be so fine. I think when things aren’t really going your way, you get subconsciously a little bit afraid of throwing strikes. When you try to make too fine of a pitch, those types of things happen.”

Cobb’s short start resulted in a de facto bullpen game for the Giants, who leaned on six relievers to cover the remaining 8 1/3 innings.

San Francisco’s pitching staff had an uncharacteristically rough weekend as a whole, surrendering 28 runs on 45 hits while dropping two of three against the Nationals.

“Generally, we just have to play better baseball,” Kapler said. “We’re going to need to make more pitches on the mound, make more plays on defense and drive the baseball a little bit more than we are.”

The Giants will now head to Los Angeles on Monday’s off-day and prepare to kick off their first series of the year against the Dodgers on Tuesday night at Dodger Stadium. The two-game set will mark the first matchup between the archrivals since their thrilling National League Division Series clash last fall, which the Dodgers won in five games.

Carlos Rodón is slated to oppose fellow lefty Julio Urías on Tuesday and will be followed by Alex Wood on Wednesday.

“It’s a classic rivalry,” Cobb said. “Both teams get each other’s best each time. You like to say that the games all matter the same, but when you’re facing a team like the Dodgers and how close of a race it came down to last year, each of those games matter a little more. I’m excited to witness in the dugout and feel a part of that.”