Bryant, despite his dislocated right pinkie, scored 41 points to help the Lakers to an intense 130-124 victory over Phoenix on Wednesday night.
Lakers newcomer Pau Gasol added 29, including a breakaway dunk that put Los Angeles up 123-117 with 1:15 to play. Lamar Odom added 22 for the Lakers, who won their sixth in a row to move into a tie with Phoenix atop the Pacific Division.
O'Neal scored nine of his 15 points in the final quarter and grabbed nine rebounds in 29 minutes against his old team in his first game in nearly a month.
"I'm in better shape than I thought I was," he said, "the adrenaline factor and just being out there with the guys."
"He did seem to get stronger as the game went on, which is incredible," Suns coach Mike D'Antoni said. "I did really think he'd run out of steam sometime in the second half, and he really didn't. Him not being used to anything that we do -- 124 points -- I didn't think we could put that many up, just starting out."
"I think everyone was excited for the game and to lose is difficult," Nash said, "but I think if you take a step back it's encouraging. I thought Shaquille was great, and I think the possibilities are very exciting."
The Lakers improved to 3-1 against the Suns, clinching the season series and knocking Phoenix out of a virtual tie with New Orleans for the best record in the West.
"The really important part of this is the season series," Los Angeles coach Phil Jackson said. "We now have an advantage if this is going to be a tight race as it's been. That's all you get out of a game like that: momentum, obviously, and some confidence for our team."
Bryant moved past David Robinson into 27th on the NBA's career scoring list.
"It was a familiar energy in the building," he said. "It felt like a playoff-type of environment. It was fun to be a part of."
O'Neal's debut came against the team he led to three NBA titles, and the visitors were in control most of the way.
Los Angeles, which routed Atlanta on Tuesday night at home, led by as many as 13 in the first half and was up 65-57 at the break.
Phoenix finally caught up when O'Neal forced a turnover, then scored on a short hook inside to make it 87-87 with 2:31 left in the period. Gasol's hook shot at the buzzer gave Los Angeles a 95-91 lead entering the fourth.
After Bryant's layup made it 105-97, rookie D.J. Strawberry twice passed to Barbosa for breakaway layups, then drew an offensive foul against Bryant. Stoudemire followed with a three-point play and Phoenix led for the first time since the early minutes 107-106 with 7:26 remaining.
The Lakers came back, though, and Gasol's three-point play with 5:43 left capped a 9-2 spurt to put Los Angeles ahead 115-108 5:43 from the end. But O'Neal scored the next six points, the last two on a goaltending call against Bryant, to cut it to 115-114. O'Neal sprinted to the defensive end of the floor after the two points.
Bryant scored inside to put Los Angeles up 117-114 with 4:04 to play. Moments later, O'Neal slammed teammate Raja Bell in the head with an elbow, forcing the Suns guard out of the game. O'Neal made one of two free throws to cut the lead to 117-115 with 3:40 to go.
Bryant's 19-footer made it to 119-115 with 2:50 to go, but Nash's two free throws, on Derrick Fisher's fifth foul, cut the lead to 119-117 with 1:49 remaining.
Odom got free for a layup, Gasol got his breakaway, and it was over.
- O'Neal dived out of bounds for a loose ball late in the third, taking referee David Guthrie down in the process.
- Stoudemire had 11 rebounds in the first half.
- Lakers coach Phil Jackson used 10 players in the first half.
- O'Neal's previous three teams (Orlando, the Lakers and Miami) were 3-0 in his debuts.
- Phoenix is home against Atlantic Division leader Boston on Friday night and Central Division leader Detroit on Sunday.