Ibaka finished with 17 points, eight rebounds and four blocks for the Thunder.
Quincy Pondexter contributed 13 points and Jerryd Bayless scored 12 as Memphis' bench outperformed the Thunder reserves. Both teams retooled their reserves during the offseason, with the Grizzlies letting O.J. Mayo leave in free agency and the Thunder trading Sixth Man of the Year James Harden to Houston.
Oklahoma City coach Scott Brooks tightened his rotation in the second half, giving Durant and Westbrook no time off even after both had played 44 minutes in a come-from-behind win at Detroit on Monday night. In that game, the Thunder scored the first 13 points of the fourth quarter to immediately erase an 11-point deficit.
Not this time.
Pondexter and the second unit brought the Grizzlies back after they'd fallen behind 30-20 after the first quarter, getting held to just 32 percent from the field. Pondexter hit a pair of 3-poitners and a couple free throws during a 16-6 burst to start the second quarter, and Memphis kept rolling as the starters rotated back in.
Another Pondexter 3 put Memphis ahead 44-41 and the Grizzlies scored the final 10 points of the half, including a two-handed dunk by Gay off of Pondexter's alley-oop, to go up 56-45.
In all, the Thunder were outscored 36-15 in the second quarter while taking their turn making just 32 percent of their shots.
The deficit ballooned to 65-49 in the first 3 minutes of the second half, with Randolph converting putbacks on back-to-back possessions and Mike Conley following Gay's 3-pointer with a runner in the lane.