49ers Lose Young for 2-4 Weeks : Pro football: San Francisco quarterback’s shoulder injury lingers; Aikman to return to Dallas on Sunday.

Did the San Francisco 49ers’ victory over the Dallas Cowboys on Sunday represent the start of another Super Bowl run . . . or a last hurrah?

That is what the 49ers must be asking themselves after quarterback Steve Young, already sidelined for a month, underwent exploratory arthroscopic shoulder surgery Monday that could cause him to sit out two to four more weeks.

The Cowboys, meanwhile, were celebrating the return of Troy Aikman, whose left knee injury was diagnosed as a bruised tendon. The injury took Aikman out of the game in the first quarter Sunday but is not expected to cause him to sit out any more games.

“Troy thinks he is going to play this Sunday [in Oakland],” said Leigh Steinberg, agent for Aikman and Young. “He is certainly happy about how things have turned out.”

Perhaps the 49ers should be, but they aren’t.

Instead of returning to the lineup next Monday in Miami as expected, Young will remain sidelined. Doctors removed bone calcification and performed a general cleanup on his left shoulder. No serious damage was discovered.

Young will sit out at least consecutive games against the Dolphins and St. Louis Rams, and possibly a playoff-type duel against the Buffalo Bills.

Even with Sunday’s 38-20 victory over the Cowboys, the 49ers are only 2-2 with Elvis Grbac at quarterback.

But Sunday’s victory helped convince Young that perhaps the team could survive while his shoulder injury, which was far more serious than first believed, could be treated surgically.

“The victory over the Cowboys was certainly a relief for everybody,” Steinberg said. “On the airplane ride home, Steve told the doctor that he felt he had plateaued, that he just wasn’t getting any better. The surgery ought to help. He can be back as soon as he recovers from it.”