(SportsNetwork.com) - The Houston Rockets and San Antonio Spurs begin a gigantic home-and-home series with massive playoff implications, starting Wednesday night at the AT&T Center.

The Rockets lead the Southwest Division by one game over the Memphis Grizzlies and 1 1/2 over the defending champion Spurs. There are so many different scenarios in play over the final week of the season.

The Spurs won their eighth straight on Tuesday thanks to a 113-88 demolition of the Oklahoma City Thunder in Oklahoma City.

Kawhi Leonard poured in 26 points in just 24 minutes and the Spurs dominated from start-to-finish to deal the reeling Thunder a fourth straight loss, which has them on the outside looking in at the playoff picture.

With Leonard leading the way by hitting 10-of-15 attempts, San Antonio shot 52.8 percent from the field en route to an eighth consecutive victory that matched a season high.

San Antonio cruised into the break owning a 63-41 advantage, with Leonard having already tallied 23 points by that time.

"We're going to need me and everyone else to step up if we're going to win another championship," Leonard said.

Tim Duncan and Marco Belinelli scored 12 apiece while Aaron Baynes, Manu Ginobili and Patty Mills chipped in 10 each.

Spurs center Tiago Splitter sat out a second straight game with a right calf injury.

Houston won three straight and seven of its last eight. Wednesday's game concludes a three-game road trip, which opened with a win in Dallas and continued with a three-point victory Sunday over the Oklahoma City Thunder.

James Harden came up big down the stretch, and the Rockets survived a nail- biter against the Thunder, 115-112, when Russell Westbrook airballed a 3- pointer at the buzzer.

Harden enhanced his MVP push with 41 points before fouling out.

Westbrook entered the game virtually tied with Harden for the scoring lead at 27.5 ppg and nearly brought the Thunder back from 13 down in the fourth frame.

His 3-pointer with 3:12 remaining evened things at 100-100, but Harden went on a personal 8-1 run over a 1:10 span to help Houston pull out the impressive victory.

Dwight Howard scored 22 points and grabbed eight rebounds in 23 minutes for the Rockets.

The Rockets never trailed after the first quarter, but a 12-1 Oklahoma City run midway through the fourth followed by Westbrook's aforementioned 3-pointer pulled the hosts even.

Harden quieted the suddenly boisterous crowd by pulling up from behind the arc on consecutive possessions and hitting 3s with a hand in his face. He grabbed an offensive rebound the next time down and made a fadeaway 14-footer, and Houston was suddenly in front 108-101 with 1:25 to play.

"We found a way to win," Rockets head coach Kevin McHale said. "The shots (Harden) made are just tough shots, and he made them. It was just a tough, hard-fought game all night."

The two teams have won one game each in the series this season, but San Antonio swept all four during the 2013-14 campaign.