Brooks scored 23 points and the Houston Rockets ended a five-game road skid with a 116-109 win over the Spurs, who spoiled a superb game from Duncan on the night he became the 35th NBA player to eclipse the scoring milestone.
Brooks wasn't sorry for crashing the party.
"You know what it was? He scored the basket and everyone yelled and it was like, 'Dang. Why's everybody yellin?' Did Eva [Longoria] come in or something?" Brooks said, referring to Spurs guard Tony Parker's actress wife.
"Then I realized it was 20,000 points, and that's incredible. That's an amazing feat, and to get a win and kinda spoil it ... sorry, that's what we're here for."
Kyle Lowry also scored 23 and Carl Landry added 19 points, leading the Rockets to their first road win since the day after Christmas. The Rockets have won three of four and return to Houston for a six-game homestand.
"We haven't had a road win in a while, so this was a good place to get one," Rockets coach Rick Adelman said.
Duncan had 25 points and 14 rebounds, and scored the last 11 points for the Spurs. But with San Antonio trailing by four with 37 seconds left, Richard Jefferson missed a running jumper that all but ended the rally.
Beaten by Utah on Wednesday, the Spurs have begun a six-game homestand with consecutive losses and continued their struggles against winning teams. Defense has long been the identity of the Spurs, but it's disappeared of late.
The Rockets shot 61 percent from the floor in the second half, two nights after the Jazz scored 60 on San Antonio in the second half.
"We're scoring more points than we've ever scored in our lives, but our defense is really sub-par and it's killing us," Spurs coach Gregg Popovich said.
Duncan struggled to pinpoint the defenses lapses.
"We're just not getting it done for enough of the game," he said.
The schedule won't get any easier. San Antonio plays three of its next four against winning teams, including division leaders Atlanta and Denver. After that, the Spurs must work through their woes on the road, taking off for virtually the entire month of February on their annual rodeo road trip.
The Rockets leaned on Landry and Lowry for this victory. The reserve duo combined for 21 points in the fourth, and Brooks added another seven.
"Tonight, me and Aaron were really able to push the tempo, and we got a lot of good things out of it," Lowry said.
The Spurs (25-17) began the second half of the season a few games off last year's pace -- an underachieving start by any measure given how much money the front office spent refreshing the roster.
Duncan joined the 20,000-point club midway through a season in which the 33-year-old All-Star has been as reliable as ever. He scored 13 points in the fourth and hit all seven of his attempts from the foul line.
Parker, dealing with plantar fasciitis, had 22 points and 10 assists in one of his best games of the season.
San Antonio led by 11 points in the second quarter but trailed 56-55 at the break after missing five of seven to end the half. More fateful was a 14-0 burst by the Rockets in the second half after San Antonio had tied it at 77.
Houston (24-18), meanwhile, hit the season's halfway point with only a few losses more than this point last year, and have done so without Yao Ming and Tracy McGrady.
The Spurs waived F Marcus Haislip before the game. Haislip appeared in just 10 games and asked to get out of his deal to pursue a deal in Europe. "He wasn't going to play," Popovich said. "There were too many guys in front of him." ...Duncan joined Dallas Mavericks F Dirk Nowitzki and Boston Celtics G Ray Allen as the other players to reach 20,000 points this season.