On Monday, the Nationals will have to make a decision on outfielder/first baseman Mike Morse, who is currently on the 15-day disabled list and is close to finishing up his rehab assignment.

The Nationals could bring Morse back on 25-man roster or outright him to Triple-A Syracuse. If Morse is back on the 25-man roster, the team will have to take somebody off it.

Roger Bernadina appears safe because he is the regular right fielder, while Willie Harris is often the outfielder coming off the bench. Willy Taveras has been getting the least amount of playing time, but he is popular in the clubhouse and has accepted his role as a reserve.

Marquis undergoes surgery on right elbow

DENVER -- Nationals right-hander Jason Marquis had surgery to remove bone chips and spurs from his right elbow on Friday. The procedure was performed Dr. Tim Kremchek in Cincinnati.

Marquis is expected to pitch in the Major Leagues in eight weeks.

"He had successful surgery to remove the loose bodies," general manager Mike Rizzo said. "He is going to start his rehab immediately, so we are looking at eight weeks down the road, and hopefully he is back helping the Nationals.

"When he comes back, it like making a trade. You get an All-Star at the Trade Deadline. The guy pitched in the All-Star Game last year. Two months from now, it will be a big boost for the club."

Marquis signed a two-year, $15 million deal with Washington this past offseason. He got off to a slow start, allowing 19 earned runs in 8 1/3 innings. The Nats began to believe that something was wrong with Marquis on April 18, when he didn't record an out and allowed seven earned runs against the Brewers.

A few days later, Marquis had an MRI and it was revealed that he had bone chips and spurs in the elbow. Marquis tried to avoid surgery. He was able to play catch and have bullpen sessions without any problems.

However, Marquis acknowledged that he didn't feel comfortable in his rehab start for Class A Advanced Potomac on Tuesday. He allowed three runs in 3 2/3 innings in an 8-5 loss to Winston-Salem. Marquis threw 54 pitches, 36 for strikes. His fastball was clocked at 88 mph, which concerned the team.

When he woke up the next day, Marquis' elbow locked up and that's when he knew that surgery was needed.

Lannan ready to make next scheduled start

DENVER -- A day after his left flexor tendon stiffened up against the Rockies on Thursday night, Nationals left-hander John Lannan played catch from 100 feet without any problems and is scheduled to make his next scheduled start against the Cardinals on Tuesday.

Lannan will have a bullpen session on Saturday to make sure he can make the start. On Thursday, Lannan made his first start since May 2. He missed an outing last Saturday against the Marlins because of elbow discomfort.

There was good news and bad news when it came to Lannan's outing against the Rockies. He cruised through the first four innings. However, after sitting on the bench for a while in the top of the fifth inning, Lannan's left flexor tendon started to stiffen up. Suddenly, he couldn't get his pitches down in the strike zone. The Rockies would go on to score four runs.

Lannan lasted 4 2/3 innings and gave up four runs on six hits. He walked four batters and struck out one. It didn't help that Lannan pitched in rainy, cold weather.

"I'm hoping for the best," Lannan said. "I'm pretty sure I'm going to kick this thing. I'm doing everything necessary to get myself ready for the fifth day. I'm not worried about what happened yesterday. It just sucks that it had to happened, but I'm not worried about it happening again. I think it happened yesterday because of the conditions."

Lannan hopes to have a better judge of how he feels in warmer weather in St. Louis.

"If this thing flares up again, then we have to talk," Lannan said. "If I don't have any problems, and I do well in my next start, then it's something to build on. Giving up those four runs is not the way you want it to end. The next start is big."

Zimmermann, Flores play simulated game

DENVER -- Right-hander Jordan Zimmermann and catcher Jesus Flores played in a simulated game on Wednesday.

Zimmermann, who is recovering from Tommy John surgery, pitched one inning, while Flores (right shoulder problems) was able to swing the bat against live pitching. Flores still hasn't been able to throw in any kind of game.

Zimmermann is not expected to play in a Major League game until sometime in September. However, there isn't any timetable as to when Flores will play in a big league game.

Once he is activated, there is a good chance Flores will be optioned to the Minor leagues. The team already has solid backstops in Ivan Rodriguez and Wil Nieves.