LAKELAND, Fla. -- Nationals right-hander Jason Bergmann, who is fighting with Levale Speigner for the final spot in the rotation, helped his cause by giving up two runs in five innings during a 6-5 loss against the Tigers on Monday afternoon.

Bergmann got off to a slow start in the first inning. With no outs and runners on first and third, Gary Sheffield hit a comebacker to Bergmann. Instead of going for the double play, Bergmann tried to get Ivan Rodriguez in a rundown between third and home. Bergmann, however, threw the ball past third baseman Ryan Zimmerman, allowing Rodriguez to score. After Magglio Ordonez singled home another run, Bergmann ended up striking out the side and shutting down the Tigers the rest of the way.

"I just really settled down," Bergmann said. "[Catcher Robert] Fick and I talked, and he was like, 'Just hit the glove; don't worry about if they're going to hit it or not.' I didn't try to do anything more than that."

With less than a week to go before Opening Day, Bergmann is not sure if he will make the 25-man roster. Last year, he was inconsistent and sent down to Triple-A New Orleans twice.

"You never take this game for granted," Bergmann said. "Anything could happen at any time. I'm not going to say I deserve to make it or I don't deserve to make it, because there are a lot of guys who are very good pitchers."

The bullpen: If the Nationals carry 12 pitchers, Chris Booker, Saul Rivera and Jesus Colome are battling for the final spot in the bullpen. Manager Manny Acta said Rivera has a "little bit of a lead," because he pitched well in 2006. Rivera pitched in 54 games and had a respectable 3.43 ERA.

"It's good that the competition is taking us up until this date," Acta said.

Booker didn't help himself by giving up the game-winning run to Ryan Raburn in the bottom off the ninth inning on Monday.

What a play! Right fielder Chris Snelling told Acta and his teammates in the second inning that he was going to throw out a runner at first base, and it occurred in the eighth inning.

Tigers outfielder Timo Perez singled to right field. While Perez took his time going to first, Snelling threw a strike to first baseman Dmitri Young and umpire Jeff Kellogg called Perez out.

"You don't see that other than Little League," Acta said. "I also didn't think that Timo didn't think Snelling was going to throw to first. He was getting ready to make a turn at first."

Injury report: Felipe Lopez woke up on the wrong side of the bed on Monday and suffered a stiff neck. Lopez took batting practice before the game, but he was a late scratch.

"I'll just take the day off and come back tomorrow," Lopez said.

Transactions: Right-handers Tim Redding and Jermaine Van Buren, outfielder Michael Restovich and infielder Bernie Castro have accepted their assignments Triple-A Columbus.

The Nationals acquired infielder Wade Robinson from the Astros for catcher Danny Ardoin. Robinson has played four seasons in the Houston system, and he hit .269 with nine home runs and 140 RBIs. Ardoin played six exhibition games for the Nationals and was 1-for-9.

The Nationals purchased infielder Matt Rogelstad from the Mariners. Rogelstad, who has played four years in the Seattle system, is a .280 hitter with four home runs and 142 RBIs.

Did you know? The Nationals are 7-5 at Space Coast Stadium and 3-9 on the road.

Coming up: The Nationals return to Space Coast Stadium to play the Mets for the fourth time this season. The Nationals have won the first three games. Washington right-hander Jerome Williams will face New York left-hander Oliver Perez at 7:05 p.m. ET on Tuesday. Williams will be making his fifth start of the season.