VIERA, Fla. -- Nationals right-hander Stephen Strasburg continues to make progress following Tommy John surgery last September. He is now throwing 90 feet on flat ground and his arm strength is slowly coming back.

The next time he throws on flat ground, Strasburg hopes to throw 15 feet further than before. There is no timetable as to when Strasburg will throw off the mound.

Once he is healthy and ready to pitch in the Major Leagues, Strasburg wants to be the ace of Washington's staff. Before he hurt his elbow in August, Strasburg was clearly Washington's best starter. In 12 games, Strasburg was 5-3 with a 2.91 ERA and 92 strikeouts in 68 innings. There is a possibility he could return to action sometime in September.

"My goal is to be the horse in this rotation," Strasburg said. "I want to go 200-plus innings every year, so it's something I'm working hard for. Physically, I feel I'm on the right track to get back.

"I have to no choice [but to be patient]. I can't just wake up the next morning expecting to get on the mound. It's a slow gradual process. It's about the slow steady progress. It has to take its time and let the body heal naturally."

Wang to throw another 'pen session this week

VIERA, Fla. -- Nationals head athletic trainer Lee Kuntz said Chien-Ming Wang's ailing right shoulder is making progress.

Over a week ago, Wang pitched in an intrasquad Minor League game, throwing one inning before leaving with a sore right shoulder. Kuntz insisted that it wasn't a setback. The team is being cautious because of the extensive surgery Wang had in 2009. He hasn't pitched in a Major League game since '09 with the Yankees.

Since leaving that intrasquad game, Wang already had one bullpen session, will have a second one this week and is working on improving his pitching mechanics.

"When we determine that he is ready to throw in a game, we will discuss it as a staff and he will go back in a game," Kuntz said. "He is making progress. He continues to get better. He is doing all the things that he needs to do.

"We have not shut him down. We haven't taken anything away from him. We are just being cautious on how we proceed, especially when you get it up to game speed. We have to see how his body reacts."

Healthy Marquis feeling great this spring

VIERA, Fla. -- Nationals right-hander Jason Marquis had another solid outing Monday afternoon in a 4-2 loss to the Tigers.

Marquis threw five innings and allowed one run on three hits. The run scored in the third, when Detroit's Cale Iorg scored on a double by Ryan Strieby. After he left, Marquis threw 20 more pitches in a bullpen session.

For the spring, Marquis has allowed the one run in 12 innings, proving that his elbow problems from last year are a thing of the past. Last year at this time, Marquis was hit hard and continued to struggle until going on the disabled list in April to have bone chips removed from his right elbow.

"Physically, I feel great. I'll keep working in-between starts to get better," Marquis said. "Last year was just bad luck. It was the first time I ever went through it. I tried to battle through Spring Training with my elbow barking.

"No excuses -- I should have been smarter about it. You live and you learn. I worked just as hard each and every year. I'm out to take the ball every five days and do what I'm capable of doing."

Marrero improving on defensive side

VIERA, Fla. -- Before this spring, Chris Marrero had a reputation of being an above-average hitter, but had problems on defense. During his Minor League career, Marrero had made 54 errors in 3,124 chances.

This spring has been a different story when it comes to Marrero's defense. He is showing more range and catching just about every ball hit to him. Marrero has made so much progress with the glove that manager Jim Riggleman predicts that Marrero will eventually be in the big leagues.

"He looks better around the bag -- defensively," Riggleman said. "He is really making a statement that he is going to be a big league player."

Marrero said hard work and changing his mental approach are the reasons he has improved with the glove.

"I think I'm more confident this year. That's the main thing," said Marrero, who was drafted as a third baseman in 2006 by the Nats. "You can work as hard as you can fielding ground balls, but if you are not confident out there, there is no point. You are not going to be catching the ground balls."