WASHINGTON -- Stephen Strasburg's second trip to the disabled list opens up a spot in the starting rotation later this week, one that Jordan Zimmermann is likely going to fill.

Baseball sources said that Zimmermann is going to start in Thursday's game against the Cardinals. The Nationals wouldn't confirm it, saying they'll give the final information tomorrow, but said that Zimmermann is getting strong consideration.

"Jordan is going to be pitching for us here in the very near future and again, that's a decision that is ongoing here," said Nationals manager Jim Riggleman. "As we make a move on the disabled list, we'll bring somebody up, and then we'll need a starter on Strasburg's day, so that could be Zimmermann."

Riggleman, and later general manager Mike Rizzo, both said the team is deciding on what to do. Rizzo said the Nationals will announce their final plans Tuesday.

Zimmermann has recovered quickly from Tommy John surgery that ended his 2009 season with the Nationals after he started 16 games. The rookie finished with a 3-5 record and a 4.63 ERA, but has done very well in rehab.

In addition, Zimmermann is scheduled to pitch Thursday, another sign that points in his direction.

"That's his day to pitch," Riggleman said. "Whether we have him go again in the Minor Leagues or have him pitch here, that will be determined here real soon."

Riggleman will miss Piniella's spirit, fire

WASHINGTON -- Nationals manager Jim Riggleman said he'll miss what Lou Piniella brought to the field as a manager every day.

Piniella retired after the Cubs' game on Sunday, ending a long and colorful career as a player and a manager. But Riggleman said he loved the spirit and fire Piniella showed, something that managers don't show as much in the game today, since most skippers don't like to say much negative.

In fact, Riggleman jokingly referred to himself as being kind of "vanilla," but said Piniella certainly wasn't.

"He would tell it like it is, and if he hurt somebody's feelings, he would deal with that later, I guess," Riggleman said. "I think that type of honesty, that emotion that comes out, I think fans miss it. Nowadays you just can't say anything negative."

Riggleman said that's the way it is with athletes in almost all sports -- except for one.

"The only time you hear anything negative is if it's a kicker in football," Riggleman said with a laugh.

Nationals extend affiliation with Harrisburg

WASHINGTON -- The Nationals announced Monday that they've signed a two-year Player Development Contract with the Harrisburg Senators of the Double-A Eastern League.

Harrisburg has played in the Eastern League since 1987 and has been an affiliate of the franchise since it signed on with Montreal in 1991.

"We are delighted to once again continue our relationship with the Harrisburg Senators," said Nationals president Stan Kasten. "Harrisburg, Metro Bank Park, the Senators and their fans have served as wonderful hosts for our players through the years. We look forward to introducing them to our next wave of exciting talent and continuing our longest-running Minor League affiliation."

The Senators have a 67-59 record in the league's West Division and sit in second place, leading Bowie by one game. The top two teams in each division make the Eastern League playoffs.