New York Knicks' Chauncey Billups shouts to his teammates during...

New York Knicks' Chauncey Billups shouts to his teammates during the second quarter in Game 1. (April 17, 2011) Credit: AP

BOSTON -- The Knicks' Big Three could be down to two Tuesday night in Game 2 against the Celtics.

Mike D'Antoni on Monday said Chauncey Billups is "very questionable" with a left knee strain. Billups, who sat in the stands and watched practice at TD Garden, said he was "really sore" a day after his knee buckled on a drive against Boston center Jermaine O'Neal late in Sunday's 87-85 loss. He missed the final 50 seconds of the game.

"This is the worst time that it could possibly happen, getting hurt in the first round of the first game of a tough series and I know the team really needs me," Billups said. "That's just frustrating, man. But that's just kind of how the ball bounces sometimes. Hopefully, I can get back soon."

How soon is unknown. Though Billups wouldn't rule out playing Tuesday night, D'Antoni said there was "more of a probability for Friday," when the Knicks host Game 3 at Madison Square Garden.

"I think everything is up in the air, day to day," Billups said. "I'm hoping it's [Tuesday], I don't know if that'll happen. I don't even know if it's realistic. Obviously, if it's not [Tuesday], I'm hoping for it to be the next opportunity."

Meanwhile, it'll be second-year guard Toney Douglas' opportunity to go up against All-Star point guard Rajon Rondo and try to lead the Knicks to their first playoff win in a decade.

Douglas, who hit a three-pointer with 37.8 seconds left in Game 1 to give the Knicks an 85-82 lead, was tripped by Kevin Garnett on a screen that freed up Ray Allen for the winning three-pointer with 11.6 seconds left. Douglas was so angry about the play that he "didn't want talk to anyone" after the game. Redemption comes Tuesday night, possibly in a starting role.

"I'm ready," said Douglas, who had eight points and two assists in 25:39. "I always prepare my mind and my body. I'm prepared already."

Douglas struggles at times to get control of the offense, especially under pressure, but his defense and shot-making ability are major strengths. He is also quick enough to keep up with Rondo and also will push the pace for the Knicks, which is what D'Antoni wants.

The Celtics had prepared for Billups, but Doc Rivers wasn't ready to say his absence would be a great advantage for Boston.

"I don't know if this helps us or not," Rivers said. "Bottom line is we are going to be worried about Rondo and all the guys on our team, not who's playing and who's playing well for them."

Douglas made nine starts this season, including six straight in early March, when Billups went out of the lineup with a deep thigh bruise. The team went 4-2 in that stretch and the experience gives Douglas something to recall.

"Most definitely, that helped me a lot, knowing that Chauncey, even though he was out, was helping me and playing with Amar'e [Stoudemire] and [Carmelo Anthony] a lot on the floor really helped," Douglas said. "My confidence is up. I'm never going to lose that."

He won't lose Billups, either. If he can't play, the 34-year-old veteran said he will "just kind of be like another coach over there."

Also thrust into a bigger role will be 35-year-old guard Anthony Carter, who played 13:30 off the bench in Game 1. Carter, like Douglas, is an aggressive defender and has the experience of 35 playoff games, including 16 during Denver's run to the Western Conference finals in 2009. Knicks fans may also remember him from his game-winning shot over the backboard in Game 3 of the 2000 Eastern Conference semifinals.

Before Game 1, Carter considered his age and the uncertainty about where he will be next season. The opportunity to play in the playoffs was something to relish. But now, there is more at stake.

"It's not about relishing anything, it's about being a professional," he said. "When somebody goes out, other people have to step up and now I'm in a situation where me and Toney have to take up the slack and play our roles."