Memphis seemed safely ahead when leading 98-94 with 3.7 seconds left.
But Jason Richardson banked in a 3-pointer to make it 98-97 with 1.1 to go, then Steve Nash fouled Memphis' Rudy Gay on an inbounds pass. The referees put 0.4 seconds on the clock.
Gay missed the first free throw and clearly intended to miss the other so time would run out. But it went in and, after a timeout, the ball moved to Phoenix's frontcourt and Grant Hill lofted a perfect lob to Richardson at the rim.
The shot went in to tie it at 99.
Nash scored 13 of his 25 points in the overtimes to send Memphis to its third loss in a row.
In New Orleans, the hosts remained unbeaten in the new NBA season after a surprise win over star-studded Miami.
Emeka Okafor had 26 points and 13 rebounds, and Chis Paul had 13 points and 19 assists for New Orleans.
David West sank crucial free throws with 7.2 seconds to go after Miami had pulled to 94-93. The Heat's Eddie House had a 3-point attempt to tie but his shot rimmed out in the final seconds.
Miami did not take its first lead until going ahead 90-89 with 59.8 seconds left, but the Hornets responded by Marco Belinelli's free throws, and then Trevor Ariza's 3.
Miami's Dwayne Wade led all scorers with 28 points, including 12 points in the fourth quarter, and went 13 of 13 from the foul line.
In Los Angeles, the home team remained unbeaten after a close win over Toronto.
Pau Gasol scored 30 points and Kobe Bryant added 23 points and six assists for the Lakers, who improved to 6-0 despite struggling to put away the Raptors, who lost their third straight.
Leandro Barbosa scored 15 of his 17 points in the second quarter for the Raptors, who have lost nine straight road games against the Lakers.
Toronto kept pace down the stretch with the two-time defending champions, out rebounding the Lakers 49-31 while L.A. coach Phil Jackson appeared to test various lineup combinations in a pressure situation.
In Oakland, Golden State extended its perfect home record by defeating Utah.
Stephen Curry returned from an ankle injury to score nine points for the Warriors over the final 2:35.
David Lee had 14 points and 15 rebounds for his fifth double double in as many games, tipping in a miss with 21.8 seconds left to help clinch it.
In Denver, Carmelo Anthony scored a season-high 30 points to lead Denver over Los Angeles.
Reserve Al Harrington added 18 for the Nuggets, who have won eight straight home games over the Clippers.
Blake Griffin had 26 points and 10 rebounds for Los Angeles, which has lost five of six to start the season.
In Philadelphia, Cleveland blew a 19-point lead before recovering in the fourth quarter to beat Philadelphia.
Anderson Varejao had 23 points and 12 rebounds, while Daniel Gibson scored 20 points for the Cavaliers, who won for the first time since the opening night of the season.
Jrue Holiday, who finished with a career-high 29 points, hit three 3-pointers in the third quarter for the Sixers to lead their rally from the huge deficit and take an 84-79 lead.
Gibson scored 10 straight points during a 19-5 run that put the Cavaliers ahead for good.
In Boston, Kevin Garnett chased down Joakim Noah and tipped the ball away from behind with 14 seconds left to allow Boston to cling on for an overtime win over Chicago.
Garnett scored 16 points with 10 rebounds, and he also drew an offensive foul with Boston nursing a three-point lead in overtime. Ray Allen, who scored 25 points, followed with a layup to make it a five-point game.
After Luol Deng tipped in an air ball, Chicago had a chance to cut it to one point when Noah tried to take off on a fast break. But Garnett ran him down and tipped the ball to Glenn Davis, who hit the foul shots to clinch it.
Noah had 26 points and 12 rebounds for Chicago.
In Minneapolis, Jamal Crawford came back from a toe injury to score a season-high 22 points as undefeated Atlanta downed Minnesota.
Josh Smith had 20 points, eight rebounds, six assists and five more blocked shots, and the Hawks improved to 6-0 despite a low-impact performance by star Joe Johnson for the second straight game.
Corey Brewer scored a season-high 18 points for the Timberwolves, who cut the lead to seven points in the final quarter but couldn't get closer.
In New York, the hosts spoiled Gilbert Arenas' return to NBA action, comfortably beating Washington.
Toney Douglas had 19 points and 10 rebounds, while Raymond Felton added 13 points and 10 assists as the Knicks' point guard combination outplayed the more heralded duo of No. 1 draft pick John Wall and Arenas, who played in his first regular-season game in 10 months.
In Indianapolis, John Salmons scored 22 points to lead Milwaukee over Indiana.
Brandon Jennings scored 18 points for the Bucks.
Danny Granger and Darren Collison both scored 19 points for the Pacers, who committed 19 turnovers.
Indiana led 76-70 at the end of the third quarter, but shot 5 for 19 in the fourth.
Both teams shot 39 percent from the field. The teams combined to score just 72 points in the second half.
In Auburn Hills, Michigan, Detroit finally notched its first win of the season, defeating Charlotte.
Ben Gordon scored 20 points and Tayshaun Prince had 14 for Detroit, whose five losses to start the season was the team's worst in 30 years.
With Rodney Stuckey benched after ignoring head coach John Kuester during Wednesday's loss in Atlanta, the Pistons started Tracy McGrady at point guard. Detroit did get Richard Hamilton (foot) and Will Bynum (ankle) back from injuries, but both played reserve roles.
Kuester, who also was criticized by Prince earlier in the week, called a team meeting to address the apparent discord after the loss to the Hawks.
In Orlando, the hosts beat New Jersey for the fourth straight time.
Dwight Howard had 30 points and 16 rebounds, finishing with 9 for 13 shooting.
New Jersey's Brook Lopez had one of the worst offensive games of the young center's career, missing his first 13 shots. He finished with 10 points, most coming far too late to prevent New Jersey's third straight loss.
Jameer Nelson scored 20 points for the Magic, who went on a 17-4 run to go ahead by 20 points early in the fourth.
