Anthony Rendon having side checked out, Casey Janssen is improving

Infielder Anthony Rendon is in D.C. today undergoing an examination on his troublesome left side with Nationals team doctor Wiemi Douoguih.

"Don't know why it's been a problem," Nationals manager Matt Williams said. "It's just crept up on him. We're being cautious with it to make sure that it doesn't turn into something we don't want it to turn into. The last couple of days, he's taken it easy. He went through the full workout a couple days ago and it was tight. So yesterday we shut him down. He's back here to see the doc today and hopefully resume."

Rendon began experiencing problems with his side last Monday when he was scratched from the lineup before his third scheduled minor league rehab game at Double-A Harrisburg. After taking five days off, Rendon was able to return to the field on Friday for five innings at second base in Harrisburg's game at Bowie. But on Saturday, the side flared up again during pregame workouts and he was forced to shut it down.

Rendon hasn't played with the Nationals since spraining his left MCL in his third Grapefruit League on March 9. Williams maintains that Rendon's knee is feeling good and it's just the nagging side issue which is preventing him from continuing daily game action.

Having scored just two runs over the past 36 innings, the Nationals offense could use Rendon's production. In 2014, Rendon batted .287 with 21 homers and 87 RBIs while also leading the National League with 111 runs scored.

The Nationals bullpen was stout the past two days, locking down consecutive 1-0 victories on the road for the first time in franchise history. Additional help for the relievers could be on the way as right-hander Casey Janssen is expected to begin his minor league rehab stint later this week. Janssen successfully pitched one inning in an extended spring game earlier today as he continues to recover from tendinitis in his throwing shoulder.

"He's gotta make sure he gets through the normal spring training-ish work," Williams said. "So that would mean getting certainly in a more competitive game, not so much controlled. So that's probably Thursday if all goes well and he feels good and then we'd have to get him a back-to-back as well like we always want to do with our relievers."

Janssen, the former Blue Jays closer, was signed in January with the idea that he would step into the eighth-inning setup role vacated by Tyler Clippard. Without Janssen, Williams has experimented with several combinations of relievers in an attempt to find some consistency.

Outfielder Reed Johnson ruptured the peroneus longus tendon in his left leg during a pinch-hit at-bat in Tuesday's 13-12 comeback win in Atlanta. Johnson delivered a two-out RBI double to trim the Braves' lead to 11-10 in the seventh inning. But he felt a pop as soon as he left the box and was forced to head to the dugout after reaching second safely.

Johnson will experience a lengthy rehab leaving Williams unsure of his availability to play again this season.

"I don't know," Williams said. "It's a question of rehab and how it comes along. So that one's kinda up in the air. We just don't know. The fact that it's repaired and put back together is good."

Johnson was hitting .222 (4-for-18) in 12 games this season.

Finally, right-hander Jordan Zimmermann faces the game's hottest hitter tonight right out of the gates. Marlins second baseman Dee Gordon's .440 batting average and 44 hits lead the majors making him baseball's toughest out heading into the series with the Nats.

"He's walking and he's hitting and he sets up their offense," Williams said. "It's important for us to keep him off the base paths so we have to make quality pitches. The free pass is something that we don't want to allow him. We want to make sure that we pitch well against him. And catch it when he hits it. He's been hot though. He's a challenge. The middle of their order is a challenge. And they're playing well as a team."

Marlins right fielder Giancarlo Stanton is a handful for most opposing pitchers. Stanton has enjoyed his trips to the nation's capital. He leads all visiting players with 14 home runs at Nats Park, while batting .336 with 27 RBIs. Overall, Stanton has blasted 23 homers against the Nats, the most against any opponent.