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9/7/2013 11:20 P.M. ET

Span returns to lineup, still day to day

MIAMI -- Nationals center fielder Denard Span was back in the lineup and batting leadoff on Saturday, a day after tightness in his right groin made him a late scratch in Washington's 7-0 loss to the Marlins.

Following the game, Span and manager Davey Johnson both said the injury was day to day. A return would be based on how Span felt once at the ballpark on Saturday, and the Nationals kept Span in the lineup after Span took batting practice.

Span extended his hitting streak to 18 games with a leadoff single on Saturday.

Harper to travel to DC to meet with team doctor

MIAMI -- Nationals left fielder Bryce Harper will fly to Washington D.C. on Sunday to visit team physician, Dr. Wiemi Douoguih, about the soreness in his left hip.

Nationals manager Davey Johnson hopes that after the visit the 20-year-old can meet the team in New York for its four-game series against the Mets.

"He aggravated [it] hitting, swinging," Johnson said following Washington's 9-2 win over the Marlins Saturday night. "He comes and hits early, then he hits in BP -- hit a great BP -- and then he goes back and hits more. I think he's got some inflammation in that hip."

Harper, who has been battling the injury and receiving treatment for it since Monday, was pulled from the lineup 10 minutes before the game when Johnson was told Harper was on the ground in the cage following a swing.

The reason for the injury remains unknown. Harper missed more than a month of the season when he banged his left knee into a wall.

Asked whether it could be an injury that ends Harper's season, Johnson said he didn't know. The second-year player is batting .273 with 19 home runs and 49 RBIs.

"It's something we need to aggressively attack," Johnson said. "I don't know. We've been kind of treating it as a slight hip strain, but obviously this is something more serious than that. We need to fix it and he needs to finish the year strong."

Harper got two days' rest on Wednesday for the series finale against the Phillies and on Thursday's off-day.

In his return to the lineup on Friday, Harper went 0-for-2 with a walk. Harper had said to Johnson before Friday's opener in Miami that he was not 100 percent, but that he still wanted to play.

"I was a little upset that he keeps swinging, you know?" Johnson said. "Instead of just resting it and going out there playing. But he's still young and exuberant and has his own routine. Hopefully it gets fixed and [he'll] be fine in NY."

Walters gets keepsake after breaking up no-hitter

MIAMI -- Nationals shortstop Zach Walters' big league debut on Friday didn't turn out quite as he imagined while playing in his backyard as a little kid.

The 24-year-old, who belted 29 home runs with 77 RBIs for Triple-A Syracuse this season before being called up on Tuesday, came in as a pinch-hitter during the sixth inning with Marlins right-hander Jose Fernandez not having allowed a hit.

Expecting a fastball on a 2-2 pitch, his dribbler down the third-base line stayed fair and gave Washington its first hit. Third baseman Placido Polanco's only play was hoping it would go foul.

"No idea where it was," Walters said. "Everyone was like, 'Run Forrest!' I kind of knew it would be a hit, and I tried not to smile after."

Fernandez gave Walters a smile once the latter reached first. Walters said during either the eighth or ninth inning, Fernandez motioned to him and put his hands up. Walters responded by showing off the ball and blowing on it.

The ball, which sat in his locker after the game, will go in his office.

"I'll tell people it was a line drive off the wall or something," Walters said.

Nats tip cap to Marlins' ace Fernandez

MIAMI -- In a division with some of baseball's top aces, the Nationals added Marlins right-hander Jose Fernandez to the list after his dominating performance Friday night.

Fernandez, vying for the National League Rookie of the Year Award, improved to 1-0 with a 0.69 ERA against Washington while flirting with a no-hitter.

At 21 years old, the Nationals know Fernandez will be a force to be reckoned with for years to come.

"He's got great stuff," said right-hander Dan Haren, who took the loss on Friday. "He's really had a great year, and he's got a real bright future ahead of him. His stuff is obviously tremendous. It's only going to get better. He's impressive."

Nationals manager Davey Johnson called it the best performance by an opposing starter against his team this season.

"He really used all his pitches, he was really attacking everybody with strikes," Johnson said. "That's key, and good location, good fastball, good breaking stuff."

The Nats, who have been shut out nine times this season, entered the game with an offense putting up solid numbers.

Washington ranked first in on-base plus slugging, on-base percentage and home runs since Aug. 9, as well as second in home runs, walks and slugging percentage in that span.

Over the past 16 games, the Nationals have posted double-digit hits 10 times. Since Aug. 9, the team has scored five or more runs 12 times.

Right fielder Jayson Werth put Fernandez's performance up there with Indians starters Justin Masterson and Corey Kluber, who beat Washington in consecutive games in mid-June.

"You see him OK," said Werth, who went 0-for-3 against Fernandez. "You're dealing with a lot of velocity. He's definitely up there as one of the best pitchers in the NL."

Worth noting

Left-hander Ross Detwiler will throw his first bullpen session on Sunday as he tries to pitch in a game before the season ends. He has been on the disabled list since July 4 with a herniated disk.

In the Minor League postseason, Double-A Harrisburg leads Erie 2-1 and plays on Saturday. Single-A Potomac swept Lynchburg, 2-0, and faces Salem for the Mills Cup Championship beginning on Saturday. Single-A Hagerstown is tied with West Virginia, 1-1, in a series that continues Saturday.

Christina De Nicola is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.