CLEVELAND -- Cavaliers starting point guard Mo Williams will miss at least one month with a sprained left shoulder, a major blow to the Eastern Conference's top team.
An MRI revealed the sprain and the Cavs said that Williams, who has played in 124 of a possible 125 games since joining Cleveland before last season, is projected to be out for the "next four to six weeks" -- a timetable that could keep him out until the first week in March.
Williams is the club's second-leading scorer and top playmaker other than LeBron James. His loss figures to test the Cavs like nothing else so far this season.
"It's huge," James said before Thursday's showdown with the Los Angeles Lakers. "The last two years a lot of the reason for the success we've had as a team is because Mo has been our point guard. He has been the guy that has kept us under wraps and played in almost every single game. When you lose an All-Star point guard it hurts. It hurts a lot.
"Guys got to step up. Guys have no choice but to step up."
Williams injured his shoulder in Tuesday night's win over Toronto when he reached for a steal in the third quarter and banged into a few Raptors players. He was taken to the locker room for an examination and treatment before returning to the floor and making a key 3-pointer in the fourth quarter.
Cleveland coach Mike Brown said it is his understanding that rest should take care of Williams' injury. It's not likely he will need surgery.
On Tuesday, the Cavs initially said Williams had sustained a strain, but changed the diagnosis to a sprain, which indicates there is a tear in the shoulder.
Williams, who was an All-Star last season -- his first with Cleveland -- scored a team-high 28 points in the Cavaliers' Christmas Day win over the Lakers.
Delonte West, who is more of a shooting guard, will start in place of Williams and Daniel Gibson will return to the rotation after having his minutes reduced in recent weeks. West will be making his first start this season.
"It's tough," Brown said. "But we feel like we have a deep team. It's unfortunate Mo got hurt because he was playing really well for us and was in a rhythm. We have to see if we can hold the fort down until he's able to come back."
Losing Williams will hurt the Cavs in a variety of ways. He is one of the NBA's best three-throw (90 percent) and 3-point shooters (43 percent).
Cleveland (32-11) entered Thursday's game against the Lakers with a 3½-game lead over Boston for the East's best record.