D.C. United defender Carlos Llamosa has a sprained left ankle and knee, and club officials probably won't know if he can play tonight against the Chicago Fire until just before kickoff at RFK Stadium.

"We expect him to start, but we probably won't make a decision until game time," Coach Thomas Rongen said yesterday. "We've had a few fluky, freaky things happen to us, and this time it's Carlos. Unfortunately, it just happened. We've dealt well with adversity and I really feel Carlos will be ready to rock and roll. He's a warrior."

Llamosa was injured during Thursday evening's practice at United Park when he slipped during an eight-on-eight scrimmage. Trainer Rick Guter said Llamosa has a mild sprain to the inside of his knee and outside of his ankle. Llamosa did not practice yesterday, and Guter added, "We'll treat him as many times as we can between now and the game. We'll have to see how well he tolerates some pain."

If Llamosa is unavailable, United (6-3, 14 standings points) will be without both of its all-star central defenders against defending champion Chicago (6-3, 18 points). Eddie Pope has missed four games with a broken foot and might return next week.

If Llamosa can play tonight, Rongen said he anticipates using the same starting lineup that produced a 3-1 victory at Miami last week. The victory increased United's winning streak to three games and moved it into a first-place tie with Columbus in the Eastern Conference.

United's group of reserves will be strengthened by midfielder-defender Brian Kamler's return from a pulled hamstring. Also, reserve midfielder-defender Curt Onalfo is almost ready after missing most of the season with an Achilles' tendon injury.

Meanwhile, United will see its possible future backup goalkeeper tonight -- on the Chicago bench. With reserve Mark Simpson out with a back injury, D.C. is interested in acquiring Jon Busch, a minor leaguer for the Hampton Roads franchise who is backing up the Fire's Zach Thornton.

Because Busch will be released next week when Chicago rookie Greg Sutton returns from an eye injury, Busch will remain in the Washington area this weekend and work out with United on Monday. United's current reserve goalie is Russell Payne, but club officials want someone more experienced until Simpson returns in about a month.

As United's lineup gets closer to normal, Rongen is hoping his club has found a winning rhythm after a slow start. D.C. did not threaten to score during the first half against Miami last week, but got two goals from MLS's leading scorer, Roy Lassiter, and a 55-yard strike from league assist leader Marco Etcheverry to pull away.

With the defending champion Fire coming in town, Rongen said his players were easily motivated this week.

"It's a big game for the guys," he said. "I can sense it. They really want to play this game. This team always responds well and looks forward to big games because that is this team's makeup. They want to compete, and they want to compete against the best. We'll be ready."

Chicago won the teams' first meeting this season, 3-2, on May 1 at Soldier Field. The Fire's comeback from a 2-1 deficit late in the game was overshadowed by Scottish referee Stuart Dougal, who handed out a league-record 10 yellow cards and one red card.

"All our players look forward to" tonight's game, Fire Coach Bob Bradley said. "D.C. is the team that everyone measures themselves against. From a player standpoint, it's a special game."

Said Lassiter: "We respect them, we respect ourselves, and I think it will be a great day for Major League Soccer."

Game: vs. Chicago Fire.

Where: RFK Stadium.

When: 7:30 p.m.

Radio: WACA-1540 (Spanish).

Tickets: $13-$34.

Records: United 6-3, 14 points; Fire 6-3, 18 points.

D.C. Probable Starters: GK -- Tom Presthus; D -- Diego Sonora, Carlos Llamosa, Jeff Agoos; MF -- Richie Williams, Geoff Aunger, Jason Moore, Ben Olsen, Marco Etcheverry; F -- Jaime Moreno, Roy Lassiter.

Fire Top Players: F Ante Razov, MF Peter Nowak, D Lubos Kubik, MF Chris Armas, D C.J. Brown.