Randolph, obtained in an off-season trade with the Los Angeles Clippers, added three blocks, while Conley had eight assists.
Grizzlies players and coaches have trouble describing Randolph's impact, from leadership to his ability to step up in the second half -- a time Memphis has stumbled in recent seasons.
"What else do you want me to say?" Grizzlies coach Lionel Hollins said of Randolph, who is averaging 18.6 points and 10.2 rebounds. "The guy has been great. He's rebounded. He's scored, and he's defended. ... He's just been outstanding for us."
Conley added: "There are too many words to describe what he's meant to this team so far. He's been an energy guy, a guy who's been a leader for this team and a veteran. Going out and putting in the work he's been doing on and off the court has been amazing."
Indiana was held to 41 percent shooting, including 3-of-21 from beyond the arc. The Pacers shot 33 percent in the second half and were outscored 56-38.
"I thought their bigs dominated our bigs," Pacers coach Jim O'Brien said. "They just dominated our people inside. We could not stop their low-post game."
Meanwhile, Memphis, near the bottom of the league in 3-point shooting, connected on 8 of 14 from long range.
Conley said he believes he's getting more open looks from the outside after trying to drive to the basket more in recent games.
"They were giving me a lot of open 3-pointers, and I was just trying to knock them down," Conley said.
The Pacers pulled to 90-82 with 7:31 left, but Randolph converted a three-point play when Hansbrough fouled him on a basket inside. Randolph then blocked two shots by the rookie before hitting an eight-footer from the baseline for a 95-82 Memphis lead, and Indiana never threatened the rest of the way.
"They put it on us," Dunleavy said. "We knew they would score a lot of points in the paint, and that they would hit the glass. We were ready for that.
"Unfortunately, they just got us in a bad way in those post ups and Randolph and Gasol just got a lot of easy baskets. That opened up the court for other guys. I thought Conley going 5-for-6 from the 3-point line hurt us a lot."
Indiana spotted Memphis an early 12-point lead but erased the Grizzlies' advantage with an 18-5 run spanning the first and second quarters to take a 56-51 lead into halftime.
Ford had 14 points in the first half, including 10 in the second quarter, to lead the Pacers. Dunleavy scored 11 in the half.
Gay had 12 points for Memphis, while Conley and Mayo added 11 each. Conley provided the Grizzlies with an unusual benefit from beyond the arc, connecting on three of his four shots from 3-point range.
Indiana turned up the defensive pressure in the second period to gain the lead. Memphis committed seven turnovers and shot 41 percent in the quarter, contributing to the Pacers' rally.
Memphis was able to open the second half with 10 unanswered points and eventually extended the lead to 79-61, its largest of the night. The Pacers missed 13 of their first 15 shots in the quarter, allowing Memphis to put together a 28-5 spurt for the 18-point lead.
Indiana would chip into the lead in the final minutes of the quarter, but still trailed 83-73 entering the fourth.
"We came in at halftime, made some adjustments, then came out and put the game away in the second half," Randolph said.
Pacers C Jeff Foster, who missed Wednesday's game against Charlotte with a sore lower back, returned to the active roster, coming off the Indiana bench. Foster had two points in just over 18 minutes. ... Hansbrough, the rookie out of North Carolina, got a rousing ovation from the crowd when he entered the game with just over 4 minutes left in the first quarter. Hundreds of residents from Poplar Bluff, Mo., Hansbrough's hometown, about 150 miles north of Memphis, attended the game. ... Memphis coach Lionel Hollins drew a technical with just over 6 minutes left in the first half after complaining about a walking call against rookie Sam Young. ... Dunleavy, who entered the game shooting 94 percent from the free throw line, missed three in a row during the third quarter and finished the night 3-of-6.
Toronto fans have nothing to cheer for in Game 5.
Take a behind-the-scenes look at the Thunder's dominating Game 4 performance against the Warriors.
LeBron James gets a steal and goes to the other end for the soaring two-handed slam dunk.