D.C. United's Thiago Martins tore the lateral meniscus in his left knee and will undergo surgery next week, club officials said yesterday.

Martins, a Brazilian forward, had just returned from a six-month layoff following major ligament surgery on the same knee and was to be available for his possible season debut Saturday against the Colorado Rapids at RFK Stadium.

An MRI exam revealed the meniscus damage but could not determine if Martins had re-injured his anterior cruciate ligament. Next week's surgery will give doctors an opportunity to examine the ligament more closely.

"For him, it's devastating for this to happen again," United President Kevin Payne said. "Rarely have I seen a player work harder coming back from a serious injury. We're hoping it's just the meniscus. Our fingers are crossed."

If there isn't any ligament damage, Martins could be back in a few weeks. But another torn ligament would sideline him for several months again.

Martins, 27, was hurt while planting his leg toward the end of a routine drill during Tuesday's practice session at the RFK auxiliary field.

Although the 6-foot, 185-pound Martins hasn't played this season, his prolonged absence is considered a big setback to United, which has been desperately seeking a physical presence on its front line for many years. This season, United (3-5-3) has scored only 12 goals for an average of 1.09 per game, seventh among the 10 MLS teams.

Forward Santino Quaranta and midfielder-forward Eliseo Quintanilla have also been sidelined all season with injuries. Quaranta has had multiple procedures for an adductor problem in the groin area, while Quintanilla continues to experience pain from a broken leg suffered in preseason.

Meantime, Payne said doctors have told starting defender Bryan Namoff, who missed last week's game at Chicago, that his abdominal injury doesn't appear serious, and that he might be ready for Saturday's match. Also, D.C. points leader Jaime Moreno (quadriceps injury) has been practicing and should be ready after missing one game.

United Notes: In a surprising development, forward Ronald Cerritos hasn't been called up for El Salvador's World Cup qualifying opener against Bermuda this weekend and will be available to play for United. However, midfielders Earnie Stewart and Bobby Convey are with the U.S. national team for the qualifying series against Grenada and will likely miss two MLS matches. . . .

The club's charitable arm, United for D.C., will collect books for local children outside Gate A on Saturday. Fans who donate will receive a key chain and ticket voucher.