Zach Randolph had 21 points and 10 rebounds for Memphis, along with a season-high seven assists as Memphis won its fourth straight. Sam Young added 12 points and Rudy Gay had 11 before leaving in the second quarter with a shoulder injury. He did not return.
Memphis, which never trailed, led by as many as 18 in the first half, then held off several runs that pulled the Sixers close in the second half.
Conley was 9 of 14 from the field in the second half, including 4 of 5 outside the arc.
Memphis had already reached a 26-10 lead after the first period, the 10 points the lowest output in a quarter for the Sixers all season. Philly was 5 of 17 from the floor in the period. Gay already had 10 points, matching the Sixers' output.
Philadelphia, which averages the second-lowest amount of turnovers per game at 14, had eight in the first quarter alone, and ended the night with 17.
Meanwhile, Memphis was holding onto the ball, not committing a turnover in the first or third periods, and ended the night with seven.
But after building the early lead, Memphis became lackadaisical, letting the Sixers make a dent in the advantage. Philadelphia did a better job of holding onto the ball, and was more accurate with its shooting.
Memphis still led 55-44 at the break.
The offensive punch for the Sixers came from the bench as Young had 14 and Williams added 10. Gay and Randolph had 11 apiece for Memphis.
But Gay went down with 5:29 left before halftime with a left shoulder injury. He was hurt on a foul by Evan Turner, shot the two free throws one-handed, unable to raise his left arm, then left the game.
Philadelphia rallied to open the second half with a 16-9 run to pull within 64-60 on Spencer Hawes' follow dunk. Meanwhile, Memphis, playing its last game before the All-Star break, seemed to lose its edge.
Six straight points by Williams pulled Philly within 71-70.
Memphis never relinquished the lead, despite the number of times Philadelphia got close, and Memphis held a 77-75 lead heading into the fourth.
The Grizzlies opened the quarter with eight straight points to create a buffer. Conley's scoring moved the lead to as many as 14, when he connected on a 3-pointer with 4:26 remaining for a 95-81 lead. Another 3-pointer by Conley about 2 minutes later, stretched the lead to 17 and the Grizzlies cruised from there.
Notes: Memphis G O.J. Mayo (three points) returned Tuesday night from a 10-game suspension for violating the league's policy on performance-enhancing drugs. He made his first appearance with just less than a minute left in the first half to a loud ovation. The Grizzlies entered last season's All-Star break having lost six of seven games. Young played high school ball in Memphis before attending Georgia Tech. Randolph's previous season high for assists was five against New Jersey on Dec. 21.