SAN ANTONIO - San Antonio has been waiting all season for guard Danny Green to get hot from long distance so when he came to life Saturday in the Spurs' 121-103 romp past the Houston Rockets, it was like welcoming an old friend back into the fold.

Green had six 3-pointers and scored 12 of the Spurs' first 14 points and forward LaMarcus Aldridge had 24 points and nine rebounds to help San Antonio beat its Texas rivals and stay unbeaten at home.

The Spurs (29-6) avenged one of their rare losses with the dominating win over slumping Houston, turning a close game in the third quarter into a rout with a 26-5 run.

Forward Kawhi Leonard added 23 points and played lockdown defense on Houston guard James Harden, holding one of the NBA's top scorers to one point in the second half.

The victory, which came against the last team to beat the Spurs (on Christmas night in Houston), was the 20th straight at home this season for San Antonio, allowing the Spurs to expand their best home start ever and extend their win streak in AT&T Center to 29 games dating to the final nine home games of 2014-15.

Green came into the game shooting just 36 percent from the floor and 30 percent from beyond the arc but hit on 6-of-9 overall and hit six of his eight 3-point attempts.

"I haven't said a word to (Green)," Spurs coach Gregg Popovich said about Green's shooting slump. "He comes in, he practices - he's a pro. There's nothing I can tell him to help. You have to participate in your own recovery."

San Antonio is just the third Western Conference team in history to open a season 20-0 at home, joining Portland (which won its first 26 games in 1977-78) and Houston (20, 1985-86).

Reserve forward Boris Diaw added 20 points for the Spurs and reserve forward David West scored 10 points for San Antonio, which hit a season-high 13 3-pointers.

Center Tim Duncan was held scoreless in almost 14 minutes, the first time in his 1,360-game regular-season career that he failed to score. San Antonio's "Big Three" of Duncan, guard Tony Parker (two points) and reserve guard Manu Ginobili (eight points) combined for 10 points. Duncan and Parker went a combined 0-of-9 from the floor.

Houston (16-19) lost for the fourth consecutive game. Center Dwight Howard led the Rockets with 22 points and 12 rebounds. Harden had 17 points (16 of which came in the first half), reserve forward Corey Brewer added 11 points and forward Trevor Ariza and guard Patrick Beverley had 10 apiece.

Green's early hot streak helped San Antonio respond to Houston's opening flurry and tied the score 14-14. Aldridge added eight points in the quarter to offset Harden's nine points for the Rockets as San Antonio, thanks to 57 percent shooting from the field, led 29-27 after 12 minutes.

"It felt pretty good to see the ball go in for me," Green said. "Even when I'm missing shots (my teammates) are always there encouraging me. Making shots makes everything better, of course. (My teammates) were excited because they haven't seen me do it in a while."

Leonard scored 12 points in the second quarter as the Spurs pushed their lead to 60-55 at halftime. The quarter had four lead changes and eight ties, the last at 50-50, but San Antonio ended the half on a 10-5 run that featured two Leonard dunks.

Brewer's 3-pointer with 2.9 seconds to play ended a wild first half in which Houston outshot San Antonio 55 percent to 50 percent from the floor.

Harden led all scorers with 16 points in the half but also picked up his third foul with 53 seconds remaining.

"We just stopped doing the things we were doing in the first half," Harden said. "They hit some shots and we stopped moving like we needed to on offense and they went on a run that we didn't answer. They play as a team and play together on both ends of the floor; they help each other."

Aldridge spent almost all of his time in the third quarter close to the basket and the move allowed him to have one of his most dominating games of the season. The Houston defender assigned to guard him, second-year player Clint Capela, had no answer for Aldridge's power moves and the Spurs' marquee offseason free-agent signee made the Rockets pay. San Antonio led 96-72 after three quarters.

"(San Antonio) knows the shots that are important," Rockets interim coach J.B. Bickerstaff said. "They want to take the 3-point shot out of the game and they want to take the rim out of the game. We had our opportunities and we created things we wanted to create but we just didn't finalize the play."

NOTES: The Rockets beat the Spurs 88-84 in the first matchup between these teams earlier this season. San Antonio has won all four of its games since, while Houston has lost all four of its contests since Christmas night. ... The Spurs closed out December with a 14-2 record, their best mark in that month in franchise history and the best mark in the NBA for the month. ... Spurs PG Tony Parker passed Scottie Pippen for 30th all-time in assists when he recorded seven Wednesday against Phoenix. ... Rockets C Dwight Howard is shooting 75.4 percent from the field in his last seven games after averaging 48.7 percent in the five games before his current surge. ... Rockets G James Harden scored 30 points in Houston's 114-10 loss to Golden State on Thursday. The Rockets have lost three of the last four games in which Harden has scored 30 or more points.