david-blatt-nba-cleveland-cavaliers-minnesota-timberwolves-850x560ESPN.com news services | 4:44 PM ET

The Cleveland Cavaliers have fired second-year coach David Blatt and are replacing him with assistant Tyronn Lue, according to ESPN sources and multiple reports.

The title-hopeful Cavaliers lead the Eastern Conference at 30-11 but were blown out by the defending champion Golden State Warriors on Monday. Blatt had lost support of the locker room over the past month, sources told ESPN’s Brian Windhorst.

Associate head coach Tyronn Lue, Blatt’s top assistant, signed a three-year contract Friday to be the team’s head coach, according to Yahoo! Sports, which also first reported Blatt’s firing.

LeBron James was not consulted before the Cavaliers made the move to dismiss Blatt and was informed of the decision Friday, sources told Windhorst. The decision to fire Blatt was “entirely” up to general manager David Griffin, a league source told ESPN.com.

Griffin is expected to speak to the media at 5:45 p.m. ET.

A team source told ESPN.com that Lue is a natural choice to assume the head-coaching job as his influence within the Cavs was already pronounced from his assistant position.

“I think it was pretty evident,” the source said. “All the guys went to him for everything anyway.”

James’ fondness for Lue and his desire to be coached by a former player also were well known in the organization, sources told Windhorst.

Sources told ESPN’s Chris Broussard that many Cavs players, especially the veterans, felt like Blatt was in over his head as coach. They questioned whether he knew the league well enough to lead them to a championship.

Blatt’s firing comes one day after the coach was defensive prior to a win over theLos Angeles Clippers. Blatt was bothered by criticism he and the team received after the 34-point loss to the Warriors.

“I hear a lot of far-reaching conclusions, and personally, I don’t like it, but there’s nothing I can do about it because I’m not the one that’s saying or doing those things,” Blatt said. “I think this team has done pretty well dealing with the adversity that we’ve had. I think this team is in pretty good position, although people choose to overlook that, which I don’t think is fair.”

Blatt leaves the Cavaliers, his first NBA coaching job, with an 83-40 record, and his .675 winning percentage was the best of any coach in franchise history. Cleveland lost to Golden State in the NBA Finals in Blatt’s first season and James’ return to the Cavs.

Even though Cleveland started the season without Kyrie Irving and Iman Shumpert for the first two months because of injuries and Timofey Mozgov(knee) and James (back) also were less than 100 percent coming out of training camp, Blatt’s second campaign was going better than his first year, when he struggled to adapt to the NBA game after being a successful coach in Europe.

According to the Elias Sports Bureau, Blatt is the first head coach since conferences began in 1970-71 to be fired when his team has the best record in its conference.

Lue will make his debut as Cavaliers coach Saturday when Cleveland hosts theChicago Bulls (8:30 p.m. ET, ABC).

Information from ESPN’s Dave McMenamin and The Associated Press contributed to this report.