Raja Bell sank two 3-pointers in the final 2 1/2 minutes of overtime and the Suns beat the Pacers 129-122, Indiana's seventh road loss in a row and eighth defeat in nine games overall.
"We're a little wounded right now, but that's the way it goes," Bell said. "You've got to step up."
Bell scored a season-high 27, including 6-of-11 on 3s. Leandro Barbosa scored 25 of his 27 points after halftime, 16 in the third quarter.
Phoenix played the final 22 minutes and 18 seconds without Nash, who left with the stomach flu. The Suns, down 14 when he left, already were without Hill, who underwent an appendectomy earlier in the day after complaining he didn't feel well at the morning shootaround.
Hill is expected to be out two to three weeks. Nash didn't travel with the team to Utah after the game, but might rejoin them for Thursday night's game against the Jazz.
"Every quarter was better and the energy was good," said Suns coach Mike D'Antoni, who added that Barbosa and Shawn Marion also were feeling ill. "It was a good win for us to come back without Steve. Steve was hurting the whole game and we are lucky to escape."
Amare Stoudemire had 25 points, including a turnaround 10-footer from the baseline that tied it with 26 seconds left in regulation. Stoudemire clinched it by making five of six free throws in the final 1:18 of overtime.
"You got to knock them down when the pressure's on and all eyes are on you," he said. "You've got to keep your composure and stay focused at the line, and that's what it's all about. My team depended on me and I came through."
Danny Granger and Shawne Williams scored 22 points apiece in a strong effort by Indiana one night after a 111-89 loss at Utah. Jamaal Tinsley scored 19, but was 8-for-26 shooting, including 4-for-18 in the fourth quarter and overtime.
"This team came in here after a blowout loss and without Jermaine O'Neal, you can't fault the effort," coach Jim O'Brien said. "The effort was exceptional."
O'Neal played Tuesday night, but struggled to just nine points. He doesn't play on back-to-back nights because of his sore left knee. The Pacers also lost Kareem Rush with a back injury and Travis Diener with a sprained right ankle in the third quarter.
Still, playing its third road game in four nights, Indiana led by as many as 11 in the second quarter and was up 85-69 after Marquis Daniels' layup with 5:32 left in the third.
The Suns used a 21-4 outburst to go up 98-97 on Marcus Banks' left-handed layup in traffic, their only lead in the third or fourth quarters. It was Banks' lone field goal.
But Williams, who fouled out in overtime, made a 22-footer and a 3-pointer in a 6-0 spurt that put Indiana back on top, 102-97, with 8:22 to go. His three-point play gave the Pacers a 108-102 lead with 6:10 left.
Both teams went cold after Marion's rebound stuff cut it to 111-107 with 5:03 left in regulation. Barbosa's two free throws made it 111-110 with 3:08 to go, then Tinsley made one of two free throws to boost Indiana's lead to 112-110 with 2:06 left in the fourth.
The Suns had three chances to tie it or take the lead before Stoudemire hit the baseline jumper that tied it. Tinsley missed a 16-footer and Phoenix got the ball with 1.1 seconds to go, but Mike Dunleavy stripped it from Barbosa at the buzzer.
Barbosa scored 11 of the Suns' last 16 points of the third quarter, eight in a 12-2 run to close the period and cut the Pacers' lead to 92-88 entering the fourth.
The Pacers shot 68 percent (13-for-19) in the first quarter to the Suns' 46 percent, and still trailed 35-31. That's because the Suns went 5-for-7 from 3-point range. ... Diener scored a season-high 12 before hurting his ankle with 1:47 left in the third quarter. ... Indiana's last road win was Dec. 17 at New York.