MEMPHIS, Tenn. -- Ja Morant shrugged off a sprained right ankle to post 22 points and nine assists, and the Memphis Grizzlies beat the Dallas Mavericks 120-106 on Friday night to advance to the NBA playoffs.

Memphis secured the Western Conference's eighth seed and will open against top-seeded Oklahoma City in a best-of-seven series beginning Sunday on the Thunder's home court.

Morant was injured Tuesday night at Golden State in the Grizzlies' play-in opener and was questionable to play Friday.

At the postgame news conference Friday, Morant confirmed that he underwent an MRI and received a pain-killing injection Thursday, and that he received another pain-killing injection before Friday's pregame warmups.

"I feel like this [injury] was more difficult than others," Morant said. "Obviously, regular-season games, it's not win or go home. So, this one was way more difficult -- the whole process, like, learning what I would have to do to be able to get out there. I was kind of questioning it, but with our staff, the doctors, they gave me all the info I needed and [in the] simplest terms so I will understand.

"From that point, it was pretty much easy. I wanted to be on the floor. I wanted to play this game and get the win."

Asked if he would continue to receive pain-killing injections during the first round of the playoffs, Morant told ESPN, "That's a question for somebody else. I'm going to be out there regardless."

Anthony Davis led the Mavericks with 40 points and nine rebounds, but limped off in the fourth quarter with what appeared to be a right calf injury. He returned briefly, but didn't finish the game. Klay Thompson added 18 points.

Davis sat in the locker room after the game with a wrap and an ice bag on the leg. He said he tried to fight through the injury, knowing it was a win-or-go-home situation.

"We had our chances. Obviously, a tough loss," Davis said.

Morant delivered a thrilling start that included a high-flying, one-handed slam dunk that had teammate Desmond Bane yelling "Showtime!" at him in celebration as Morant elevated so high his eyes were level with the rim.

Morant, who scored 16 points in the first half, said of his sprained ankle, "I couldn't feel it ... so I was out there."

"I've learned not to doubt him too much," Grizzlies interim coach Tuomas Iisalo said of Morant. "He comes up with some stuff that I'm not sure there's any other human being on the planet that they can do stuff like that."

Morant occasionally limped to the free throw line, but that was about the only sign he was playing hurt. He finished with 9 rebounds, 7 assists and 3 steals before interim coach Tuomas Iisalo pulled his starters in the final couple of minutes to get some rest.

Morant wound up playing 33 minutes, helping the Grizzlies finish off a wire-to-wire win.

"I honestly feel like I could have been better," he said. "But any day you can wake up and go do what you love at the highest level, you should have fun. So, yeah, it felt good to get a win and have smiles around here."

Memphis has lost nine straight to the Thunder by an average of 16.9 points per game, including four straight by double figures this season. Jaren Jackson Jr., who led Memphis with 24 points on Friday night, said the Grizzlies are looking at a different situation in the first round.

"A series is a series," Jackson said. "You've got to stay level-headed. Whether you win a game or lose a game, it really doesn't matter until it's over."

The Associated Press contributed to this report.