SAN FRANCISCO -- The Giants will bring some uncertainty along for the ride as they head down south for a brief four-game road trip in Arizona. 

After missing the first three weeks of the 2023 season with a left hamstring strain, Austin Slater could miss additional time after exiting Wednesday's 11-6 loss to the Nationals in the sixth inning with left hamstring tightness.

"It's definitely very frustrating," Slater said. "It just doesn't feel like I can catch a break right now. Hopefully it's nothing major."

Slater will get imaging done on the area on Thursday to determine the scope of the injury. Manager Gabe Kapler said it's a concern, but the Giants' training staff is cautiously hopeful that it's minor.

"[Head athletic trainer Anthony Reyes] was optimistic that it was more tightness than a surefire strain," Kapler said.

Facing Nationals right-hander Josiah Gray with Michael Conforto on third and two outs in the bottom of the sixth, Slater tapped a slow roller that trickled toward shortstop Ildemaro Vargas. Given Slater's speed and the way the ball was positioned, it should have gone for an RBI infield single.

But Vargas made a quick throw, and Slater had slowed down a few strides short of the bag. He said he had pulled up as soon as he felt tightness in his left hamstring, which flared up as he was running down the line. Slater said Wednesday's hamstring tightness didn't feel as bad as the injury that sidelined him during spring.

Since making his season debut on April 24, Slater has slashed .368/.455/.421, driving in two runs and scoring three. He appeared in eight of the team's 15 games since his activation, getting days off to help ease him back into action, and his right-handed bat has brought more balance to a lineup that struggled to hit lefties early in the season.

Slater's early departure was a shadow over an already disappointing day at Oracle Park. The Giants dropped the midweek series to the Nationals after taking four of their last five, winning two games each against the Astros and Brewers, who were both above .500 at the time.

Left-hander Sean Manaea turned in one of his shortest starts as a Giant, getting charged with eight runs (four earned) and failing to make it out of the third inning. 

"All my stuff just sucked," he said. "That's really what it comes down to."

Though he began his day with a 1-2-3 frame, Manaea quickly had no answer for the Nationals' pesky bats. Washington's offense put up four-spots against Manaea in the second and third innings, though all of the runs scored in Manaea's final frame were unearned after J.D. Davis bobbled a Jeimer Candelario grounder.

Manaea allowed five hits through 2 2/3 innings, but the real dagger was his command. He issued three free passes, and all of them scored.

"When all of those walks score," Manaea said, "it tends to be a bad day."

Kapler said the team will dissect what exactly went wrong during Manaea's outing, but he was proud of the way the Giants' bats were able to chip away at the gaping deficit. San Francisco was down by eight runs entering the bottom of the eighth, but a pair of two-run homers gave the team a little more life when all was said and done.

Conforto, who had not recorded a hit since the club's 2-0 win in Houston on May 2, went deep in the eighth inning to snap an 0-for-20 stretch. LaMonte Wade Jr., who extended his career-best on-base streak to 16 games, added on another two-run shot in the ninth.

It was too little, too late in the end, but Kapler said his team's nine-inning effort will bring dividends going forward.

"Even though it's at the end of the game, maybe not deciding the game, it's still a big confidence boost," Kapler said. "Every time these guys go up to the plate and drive a baseball, they need to carry that into the next at-bat, and I think it was an important moment for us."