PITTSBURGH — Who's on first?

It's a legendary Abbott and Costello comedy routine. It's also a legitimate question for the Pittsburgh Pirates since the trading deadline deal of Sean Casey to Detroit.

Besides Casey, the Pirates have used Craig Wilson, Xavier Nady, Ryan Doumit, Jose Hernandez and Joe Randa at first base this season.

Wilson has since been traded to the Yankees. Hernandez has since been traded to the Phillies. Randa is considering retirement and won't be here next year.

That leaves Doumit, Nady, injured prospect Brad Eldred or someone from outside the organization to man first base for the 2007 Pirates.

"These final 12 games are very important to me in that regard,"Doumit said. "I've missed three months. That definitely affects your timing at the plate."

While Nady has spent time at first base in the major leagues — he started 34 games at first base in 2005 with San Diego — he also led all National League rookies with 12 assists from the outfield in 2003.

Before being traded to the Pirates this season, Nady started 70 of 71 games with the New York Mets in the outfield.

"It doesn't matter to me ... I can certainly play there,"the 27-year-old said of first base.

Pirates general manager Dave Littlefield likes the flexibility Nady's presence on the roster provides.

"I don't see him being pigeonholed into one position,"Littlefield said. "Xavier will likely see time in right field and at first base.

"You like having flexible players. It guards against injuries and you can give guys days off."

Nady has not been an everyday player in the big leagues before this season. He is hitting .279 with 16 homers and 57 RBIin 416 at bats, snapping an 0-for-21 slump with a double Sunday.

"I'm like anybody else,"Nady said. "I just want to play."

So does Doumit. That's why he had no problem giving first base a try this season, despite having never played the position before in his life.

A hamstring injury put Doumit on the shelf for three months, taking away his defensive development and his batting stroke.

"I'm still learning the nuances of the position," he said of first base. "There's a lot of footwork involved over there that's still foreign to me."

Coming up through the Pirates system as a catcher and occasional outfielder, Doumit's last 14 starts have been at first base. He has committed just two errors in 153 chances at the position, but is hitting just .216 with five homers in 116 at-bats through Tuesday's game.

Of his 25 hits this year, 13 have been for extra-bases.

Eldred, 26, was the heir apparent to Casey at first base for the Pirates before a fractured thumb required surgery April 25, sidelining him for the season.

Eldred hit 40 homers and drove in 102 runs between Class AAAltoona, Class AAAIndianapolis and the Pirates in 2005, including 12 homers and 77 strikeouts in 190 at bats with the Bucs.

"He's been swinging the bat well in Bradenton, and Brad will be going to the Florida Instructional League next month,"Littlefield said. "We're anxious to see how he performs in game action."