NEW YORK -- It's only been four games, but Nationals slugger Adam Dunn has been solid playing first base. He looks better coming off the bag and doesn't have any problems scooping balls out of the dirt.

It looked like Dunn couldn't do anything last year right after being switched from left field to first in July. Dunn had little range around the bag and had problems fielding hard-hit ground balls.

So what's the difference this year? Dunn works extremely hard before games. Last year, according to third-base coach/infield coach Pat Listach, it was tough to get Dunn to practice early before games.

"He is working harder," Listach said. "[Last year], it was kind of tough to get him out there and wear him out at first base -- early work. Starting in Spring Training, he will work at first base, do his drills and get his ground balls. Yesterday, even though we had a 4:30 game, I had him out there early. I said to him, 'We are going to be on the road the next seven days, and we are not going to work on the field early. Let's go out and get some work done.' He got his work done."

The biggest advice Listach and Tim Foli, the team's senior assistant to the general manager, told Dunn is to focus on every pitch. So far, he has yet to make an error or mental mistake.

"I know I'm in the right position and not having to think out there. I have to react. It's having fun," Dunn said. "It's a lot easier to do something when you know you don't have to think every two seconds.

"All the work that we did in Spring Training, you are seeing the results now. I'm relaxed and not thinking. [I am] just reacting."

Dunn acknowledged that his attention span wasn't where it should have been while playing in the outfield.

"I think that was a lot of the problem," Dunn said. "The problem was never catching the ball, it was getting bad jumps."

Strasburg's debut to air on MLB.com

WASHINGTON -- Nationals right-hander Stephen Strasburg makes his Minor League debut for Double-A Harrisburg on Sunday at 2 p.m. ET, and MLB.com is planning on streaming the game. Strasburg is expected to pitch five innings, or throw 85 pitches, against Altoona.

Guzman may start Sunday in right

WASHINGTON -- Manager Jim Riggleman said that Cristian Guzman will start at second base against the Mets on Saturday afternoon and may start in right field the next day.

Sunday's start will hinge on how Mike Morse is doing. Morse suffered a strained left calf Wednesday against the Phillies. He said he can do pinch-hitting duties without any problems, but can still feel some pain while running the bases.

As for Guzman, Riggleman is reluctant to put the veteran in right field because sun can be tough on outfielders at Citi Field.

"Guzzie has been such a pro and he is really swinging the bat well," Riggleman said. "From the right side, I hate to not play him when a left-hander is pitching. I'm going to try to find a place for him somewhere."

Left-hander Johan Santana pitches on Sunday for the Mets.

Walker helps Capps fix delivery

WASHINGTON -- Thanks to reliever Tyler Walker, closer Matt Capps was able to pick up his first save of the season Thursday against the Phillies.

After Monday's game, in which Capps gave up an unearned run, Walker realized he and Capps have similar deliveries. He then noticed Capps was turning his head and opening up his front shoulder too much, a problem that plagued Walker as well.

Walker told Capps, who followed the advice and fixed the flaws.

"It's big time to get the advice," Capps said. "We were talking in the outfield during batting practice. Our mechanics and delivery are a lot alike. He heard me talking and he has similar problems that I have."

Capps and Walker cut a deal that they would help each other whenever they have problems on the mound.