The San Antonio Spurs moved to within one victory of securing the Western Conference top seed for the playoffs on Sunday as the NBA's leading contenders continued to jostle for position in the final week of the regular season.

The Spurs easily defeated Cleveland 114-98, after Oklahoma City suffered a heartbreaking double overtime defeat to the Los Angeles Lakers, handing San Antonio a one-and-a-half game advantage over the Thunder in the conference.

San Antonio, who would finish ahead of Oklahoma City by virtue of the tie-breaker between the teams should they finish level, can clinch the top seed with a victory over Portland on Monday.

Oklahoma City sustained a blow in their 114-106 loss to the Lakers in a physical battle that saw Los Angeles forward Metta World Peace ejected after hitting James Harden with an elbow to the head in the second quarter.

World Peace was celebrating a dunk when he flung an elbow at Harden, knocking his opponent out of the game with a concussion and earning himself an early shower.

""It was unfortunate that James had to get hit with an unintentional elbow," World Peace told reporters, following actions that will likely see him face a suspension.

""I hope he is OK. I apologize to the thunder and to James Harden."

The incident overshadowed a thrilling showdown that featured clutch shooting from Kobe Bryant, who had 26 points, and a game-high 35 points from Kevin Durant.

The Lakers moved a game in front of the Los Angeles Clippers, who are playing later on Sunday, for third in the West.

Meanwhile, Denver slipped a half-game in front of Dallas for sixth in the same conference following their 101-74 blowout of Orlando.

In the Eastern Conference, Carmelo Anthony scored 39 points to help the New York Knicks edge Atlanta113-112 and move a half-game ahead of Philadelphia for seventh in the East.

A shorthanded Miami Heat beat Houston 97-88 behind 32 points from LeBron James. The Heat trail East-leading Chicago by two games with as many contests remaining.