WEST PALM BEACH, Fla. -- Victor Robles’ hot night at the plate was cut short in the fifth inning Friday when he left the game because of “a little back tightness,” according to manager Dave Martinez.

“As a precaution, we took him out,” Martinez said after the Nationals’ 10-9 win over the Astros at The Ballpark of the Palm Beaches.

Following Carlos Correa’s ground-ball single to the outfield, Martinez and trainer Paul Lessard ran out to check on Robles. Fourth outfielder candidate Andrew Stevenson was already on the field before Robles walked off to receive treatment.

“He actually did it before the throw,” Martinez said. “He kind of slipped a little bit when he went to go throw the ball. We saw him go backwards a little bit. We’ll see how he feels [Saturday].”

Robles had been doing damage on offense prior to his exit. He doubled to left field in the first at-bat of the game, and he belted his third home run of Spring Training in the fourth, a solo shot to center field.

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The 23-year-old has been thriving as the Nationals take a look at him in the leadoff spot. He is slashing .313/.405/.688 in 12 games. In addition to the trio of homers, Robles has tallied 10 hits, three doubles, four RBIs, nine runs, four walks (against 12 strikeouts) and four stolen bases.

“The biggest thing for me is that he’s limiting his chase,” Martinez said. “He’s getting the ball in the strike zone, and he’s staying on the ball. He’s hitting it hard. His two-strike approach is getting better, which is good. So far, I like everything that he’s done. He’s taken his work into the games -- which is really, really nice -- and he’s having good at-bats.”

The Nationals also received home runs from Josh Bell (his team-leading fourth of the spring) and Josh Harrison (his second) on Friday night.

Strasburg's sim game
Stephen Strasburg continues to progress in his return from the left calf discomfort that caused him to leave last Sunday’s start early. On Friday, he built up to five innings in a simulated game. He threw 74 pitches to catcher Alex Avila, and the veteran right-hander faced Jordy Mercer, Hernán Pérez, Tres Barrera and Luis García.

“He looked good,” Martinez said. “He had nothing that indicated that his calf was bothering him. He felt strong. He kind of tired at the end there a little bit, but he got through it.”

Espino 'doesn't give in'
Following pitching changes in the Nationals’ throwing schedule with Jon Lester and Joe Ross, Paolo Espino got the start Friday night. He fanned two and allowed a pair of hits and one run over two innings. Martinez said Espino received the nod because he is a pitcher they could consider calling up if there was a need to “fill a void,” and they wanted to get him stretched out. The 34-year-old right-hander threw six innings (including one start) with a 4.50 ERA last season for the Nats.

“He throws strikes,” Martinez said pregame. “He’s a veteran guy, he knows how to get outs, he doesn’t give in.”

Top 30 prospects optioned
The Nationals made their second round of roster moves, optioning MLB Pipeline-ranked prospects catcher Tres Barrera (Nationals’ No. 19), left-hander Ben Braymer (No. 21) and right-hander Steven Fuentes (No. 22) to Triple-A Rochester.

Barrera has appeared in eight games as a potential third catcher. Martinez said on Thursday, “He’s got to continue to learn, continue to develop, but he’s knocking on the door.”

Braymer (3 2/3 innings, five hits, three runs, one strikeout, 7.36 ERA) and Fuentes (4 innings, three hits, one unearned run, four strikeouts, 0.00 ERA) were vying for bullpen spots.