Amare Stoudemire led six Suns players in the double digits on the way to a 96-79 victory over the defending champions on Wednesday night.
"Anytime you come here it's a good win," Steve Nash said. "But we're also still fighting for seeding. It gives us another possibility as far as seeding goes."
The Suns won their second game in a row on the second night of a back-to-back and remained in sixth place in the Western Conference.
Shaquille O'Neal had eight of his 16 points in the decisive fourth quarter and grabbed nine rebounds for Phoenix. Nash scored 12 points -- including eight in the fourth quarter -- and had 10 assists.
O'Neal was back after missing Tuesday's game with a right hip contusion.
"I played through everything," O'Neal said. "I told them that if they play me single coverage, let me make them pay. I'm still the baddest 36-year-old ever created."
O'Neal said he took it as an insult that the Spurs didn't double him late.
The two teams continue to jockey for seeding in the West, but Wednesday's result didn't change their positioning. San Antonio remained in second place behind New Orleans.
Though they're four seeds apart, just a half-game separates the Spurs and Suns, who could match up with any number of teams in the first round -- including each other. The two had a physical and testy second-round series last year that San Antonio won in six games on its way to the title.
On Wednesday, Stoudemire started down that road again, this time during the regular season.
Spurs forward Bruce Bowen ran into Stoudemire in the fourth quarter, upsetting the Suns center.
"Bruce came elbow first. Elbowed me right in my rib cage," Stoudemire said. "You know, definitely wasn't a basketball play on his part and I reacted. I definitely didn't appreciate it. So, I let him know about it."
Bowen didn't talk postgame.
During last year's playoff series, Stoudemire called the Spurs a "dirty team" and singled out Bowen in particular.
Up by four points with a quarter to play, O'Neal and Nash helped Phoenix pull away in the fourth, spearheading a decisive 13-0 run to go up by 19 points -- 92-73 -- with 3:52 to go. Not long after, Spurs coach Gregg Popovich cleared his bench.
Phoenix outscored San Antonio 24-11 in the fourth.
"Defense was solid. The offense just couldn't sustain -- miss after miss. A lot of that falls on me. I got a lot of shots in the fourth quarter, what I felt were good looks. They just didn't go down for me," said Duncan, who was 1-of-5 from the field in the fourth quarter.
Last week in a 90-64 loss against Utah, the Spurs scored 26 in the second half and nine in the fourth quarter. They beat Portland 72-65 on Sunday.
"It's turned into a concern because that's three games we really struggled offensively," Manu Ginobili said. "We didn't score more than 80 this weekend. The main concern is offensively. We're just not sharp enough. We're not making shots. We're playing too slow. So we've got to work on that."
Michael Finley added 10 points for San Antonio.
The Spurs jumped out to an early lead off of the Suns' poor shooting, but Phoenix fought back in the second quarter, taking a brief lead during an 8-0 run highlighted by Nash's first score of the game and six straight points from Stoudemire, who hit his second of back-to-back dunks over Duncan off a no-look pass from Nash.
The teams were tied 45-45 at the half.
After three quarters the Suns had improved their shooting to better than 50 percent and while Nash still wasn't scoring, he was dishing the ball left and right to find openings for teammates.
Diaw's dunk -- off a pass from Nash -- put the Suns up 67-66 with 2:20 to go in the third and was part of Phoenix's 11-2 run to close the quarter and take a 72-68 margin with 12 minutes to go.
The Suns -- the league's top 3-point shooters -- also started hitting from beyond the arc. They had two 3s as part of the third-quarter closing burst and Barbosa opened the final period with his second 3 of the night.
The Suns won the season series 3-1. ... Of the race for seed position in the West, Popovich said pregame: "It's been a real competitive year more than any other year and the playoffs will be fantastic because of that. ... There are no favorites really, it doesn't matter what the seeding is going to be, the seeding is really irrelevant." ... The Suns finished 4-of-11 from 3-point range. The Spurs were 2-of-9.