James Paxton believed that he had returned to full strength, less than six months removed from back surgery, though the Yankees left-hander cautioned that he was still hoping to find a few more ticks of velocity as he prepared for his season debut.

Absent that extra sizzle on his fastball, Paxton struggled to put away the defending World Series champions, recording only three outs as the Yankees absorbed a 9-2 loss to the Nationals on Saturday night in Washington.

• Box score

“I didn't feel great,” Paxton said. “I didn't really have the good fastball, didn't really have a breaking ball to put guys away with. I was able to get to two strikes on some guys but just couldn't make pitches to put them away. It was just not a good night for me.”

Paxton used some decent curveballs and cutters to pitch around Starlin Castro’s two-out triple in the first inning, but three singles quickly loaded the bases in the second. Victor Robles lashed a two-run double down the left-field line, and Paxton was lifted one batter later, having thrown 29 of his 41 pitches for strikes.

In early February, Paxton underwent a microscopic lumbar discectomy during which a herniated disk was repaired and a peridiscal cyst was removed. Paxton’s fastball averaged 91.8 mph on Saturday and topped out at 93.8 mph, down from his 2019 average of 95.4 mph.

“I'm not alarmed. I feel like physically he is sound,” manager Aaron Boone said. “I think it's just a matter of really getting his delivery and finding that click where he's really extending through the ball. That's kind of what he's been searching for here these last few weeks.”

Paxton said he believes the velocity will increase as he continues to pitch.

“I think it will come with time, but it’s definitely something that I want to address and look at going forward,” Paxton said. “There’s no pain at all in throwing. I just felt a little sluggish tonight and my arm didn't feel like it was really live.”

Michael King escaped the second-inning jam with minimal damage, inducing a run-scoring double-play grounder and a flyout. King served up a two-run homer to Robles in the fourth inning and a run-scoring Howie Kendrick double in the fifth, charged with four runs and four hits over 3 1/3 innings.

“I thought he pitched great,” Boone said of King. “Really, the one mistake I thought he made was the two-strike hanging breaking ball to Howie Kendrick. Otherwise, we continue to be really encouraged by what we see from Michael.”

Giancarlo Stanton launched a mammoth homer off Nationals right-hander Erick Fedde, who allowed two runs over four innings in a spot start after ace Stephen Strasburg was scratched due to a right hand issue.

Stanton’s second homer in as many days cleared the bullpen in left-center field and was projected to have traveled 483 feet with an exit velocity of 121.3 mph, according to Statcast.

“It wasn't enough to get us the win tonight, so that's most important,” Stanton said. “I've got to continue it tomorrow.”

DJ LeMahieu added a run-scoring single in his season debut, playing five innings at second base. LeMahieu said he plans to play nine innings on Sunday.

With King having pitched in relief, Boone said he would meet with his coaching staff to decide between right-handers Chad Green and Jonathan Loaisiga to open Sunday’s series finale (1:05 p.m. ET, live on MLB.TV).

Roster moves
The Yankees announced after the game that they optioned outfielder Clint Frazier and right-hander Ben Heller to their alternate training site in Moosic, Pa. The team plans to recall right-handers Brooks Kriske and Nick Nelson as additional bullpen arms.

“I feel like we're in pretty good shape,” Boone said. “We're going to go talk through some things and figure out how we want to go.”