Bryce Harper returned to the Nationals' lineup on June 30 after missing more than two months with a torn left thumb ligament.
It was the first time since Opening Day that manager Matt Williams was able to put his full lineup on the field, as the injury bug bit Washington early and often with both Ryan Zimmerman and Wilson Ramos also missing extended time at various points during the first half of the season.
The Nationals -- who will open a three-game set at Cincinnati on Friday -- enjoyed tremendous success during their healthy stint in July, compiling a 12-5 record in 17 games. But on Tuesday, less than month after returning to full strength, Zimmerman strained his right hamstring beating out a double-play throw to first base in the sixth inning, resulting in his second trip to the 15-day disabled list this season.
"He's pretty sore today," Williams said Wednesday of Zimmerman, who missed 44 games earlier this year with a fractured right thumb. "It's actually a little worse [than it was Tuesday night]. When I spoke with him this morning, he hadn't had any treatment on it. When you're hot and it happens, it doesn't feel as bad as it does the next morning."
The Nationals recalled infielder Zach Walters from Triple-A Syracuse to take Zimmerman's roster spot.
Moving forward to the series against the Reds, Danny Espinosa will return to the starting lineup at second base while Anthony Rendon will move to third -- a defensive alignment Williams used during Zimmerman's absence earlier in the season and during Wednesday's loss to the Rockies in the series finale at Coors Field.
"You don't ever want to see that happen to any of your teammates," first baseman Adam LaRoche said. "But a guy who has battled back from one injury and is a core piece of your lineup, that stings a little more."
The Reds, meanwhile, enter Friday's series opener against the Nationals on a six-game losing streak, including sweeps at the hands of the Yankees and Brewers in the last two series.
"We don't just all jump on a flight to Cincinnati and everything is fine. It's not," Reds manager Bryan Price said after Wednesday's 5-1 loss in Milwaukee. "We live this life. There's carryover. The best thing we can do is go home and try to enjoy a day off and just clear our minds and come back and be ready to go and play the game ... the way we know how to play it. We've gotten away a little bit from what we do. We just need to get back there."
Right-hander Alfredo Simon, who sports a 12-4 record and a 2.74 ERA this year, will look to stop the skid against Nationals right-hander Tanner Roark, who continued his breakout season on Saturday by earning his team-high ninth win with seven innings of one-run ball against the Brewers.
Reds: Negron OK after taking pickoff throw to head
In the top of the ninth inning of the Reds' 4-3 loss to Brewers on Tuesday, infielder Kristopher Negron took a lead off first base when Milwaukee closer Francisco Rodriguez attempted a pickoff throw.
The ball drilled Negron in the side of the head near his ear where there is no protection from the helmet. He remained on the ground for several minutes and was examined by a trainer before remaining in the game.
Negron reported no headaches or wooziness in the aftermath of the incident, meaning he didn't have to undergo any further testing as far as the league's concussion protocol.
"It got me right behind the ear," Negron said on Wednesday. "It caught me pretty solid. I was a little dazed right when it happened, but it went away quick. I am good to go now."
Nationals: Werth sits with sore knee
Jayson Werth awoke on Wednesday morning with some soreness in his right knee, so he texted Williams to inform the first-year skipper of the issue.
With the Nationals scheduled for a day off Thursday, Williams opted to keep Werth out of the starting lineup on Wednesday for the team's 6-4 loss to the Rockies.
"We hope having two days off will help it calm down for him," Williams said. "We'll give him some treatment and some anti-inflammatories. I think he's fine. It's one of those things where you go through the season and things creep up on you, so if we can, we need to give him a day."
Werth entered Wednesday's game in the seventh inning to pinch-hit for Scott Hairston. He struck out in the at-bat before playing the final two innings in right field. Werth got another at-bat in the top of the ninth inning and drove in a run with an RBI single to right.
• Reds shortstop Zack Cozart was absent from the starting lineup on Wednesday after getting hit by a pitch on the right hand Tuesday night. His pending return is listed as day to day.