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Courtney Lee will play a big role in helping to replace Rajon Rondo's void.

Courtney Lee knew when he was traded from the Rockets to the Celtics last summer that he would have to accept a smaller role in Boston's guard-heavy rotation.

But losing Rajon Rondo for the season with a torn right ACL changes that. It changes everything, really. And as the Celtics prepare to gather themselves and press on with the remainder of the 2012-2013 campaign, Lee knows he'll be one player shouldered with greater responsibilities.

"It's definitely going to be tough. Nobody can fill [Rondo's] shoes," Lee said after Sunday's 100-98 double overtime victory over the Miami Heat. "That's what makes him great. The only thing we can do is work as hard as possible and keep the momentum going from this game and have no let-up."

No one knows exactly what the Celtics will look like moving forward without their best passer and play-maker, who handled the ball more than anyone else on the team. Lee's new responsibilities aren't set in stone yet, but he'll likely be distributing the ball more and helping to initiate what, in all likelihood, will be a simplified Boston offense for the foreseeable future.

Will Lee start alongside Avery Bradley? He could. Head coach Doc Rivers elected to start Lee in place of Rondo against the Heat on Sunday, and he's done the same at other points this season when Rondo missed games due to injuries or suspensions. But with the bench playing some of its best ball in recent weeks, Rivers might want to keep as much continuity there as possible. He was already hesitant to insert Jared Sullinger into the starting lineup against Miami on Sunday, and he might have similar reservations about Lee.

The good news for the Celtics is that Lee has had some of his finest games of the season when Rondo's been out of the lineup. In the six games Rondo's missed this season, Lee has averaged 32.5 minutes, 10.5 points, 4.3 rebounds, 2.3 assists, and 1.8 steals -- all higher than his overall season averages. While the increased minutes (Lee's averaging 22.8 minutes per game for the season) have likely played the largest role in the greater production in those games, Lee also had more freedom with the ball to penetrate and make plays for himself and his teammates. The only sour note? Boston's just 3-3 in those six games.

Becoming more of a play-maker might be Lee's greatest task moving forward. The Celtics are still a jump-shooting team, so they'll need someone to try to penetrate into the lane and force the defense to collapse to free up outside shooters. Lee's shown flashes of being the kind of player that can knife through a defense and set up shots for other guys.

Boston might also put an even greater emphasis on its transition play. With Rondo out and the halfcourt offense likely simplified, the Celtics would do themselves a great service by pressing harder on fast breaks and generating as many easier buckets and looks at the basket as possible. Lee's proven he can excel in this area by beating the defense up the floor or finishing at the rim while facing contact from opponents.

He's not Rondo, and he's not going to post Rondo-like numbers, but Lee having more freedom with the ball and playing with a determined effort every night will likely be one of Boston's preferred options moving forward.

"We can't match it. [Rondo] is who he is," Lee said. "He's been an All-Star, he [was] starting for the All-Star team this year. So, what me and Avery are going to do is we'll probably split some of the minutes and even [Leandro] Barbosa, also. We have to go out there and play solid, compete every night, make sure we know our plays, get people in the right spots, and just go out there and execute."