OKLAHOMA CITY - Zach Randolph and the Memphis Grizzlies powered their way to another playoff upset — not that he considers it one.

Randolph had a playoff career-high 34 points and 10 rebounds, Marc Gasol added 20 points and 13 boards, and the Grizzlies outmatched the Oklahoma City Thunder inside for a 114-101 victory in the opening game of the Western Conference semifinals on Sunday.

"We believe," Randolph said. "We definitely believe. Our confidence is up high. I tell the guys we can compete and play with anybody."

Just as they did in a first-round upset of top-seeded San Antonio, Randolph and Gasol provided enough punch to give eighth-seeded Memphis a road victory in Game 1.

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Randolph and Gasol each scored 20 points in the same regular-season game only once this season, but did it in Game 1 against the Spurs and again to negate the Thunder's home-court advantage right from the start.

"I think we always try to do that. The thing is that it's not always possible," Gasol said. "We always try to come out and execute and play the right way. It's not always possible. Teams are going to adjust, and they're going to do something different.

"We've got to keep being hungry, keep being unselfish offensively and defensively and keep playing the right way."

Game 2 is Tuesday night in Oklahoma City.

Kevin Durant led the Thunder with 33 points and 11 rebounds. Russell Westbrook scored 29, but the All-Star tandem couldn't overcome a big advantage in the paint for Memphis.

Randolph had two games with at least 30 points and 10 rebounds in the regular season against the Thunder, as Memphis won the series 3-1. And he was at it again from the tip, scoring the Grizzlies' first seven points to provide them a lead they wouldn't relinquish.

"You can't stop him. You've got to make them shoot tough shots like he's been doing, but if he's making them, he's tough to stop," Durant said.

"He's an animal."

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Durant went on to say that he considers Randolph, a 10th-year veteran who's bounced around the league with no postseason success until this year, to be "the best power forward in the league."

"I've got to agree with that. Thanks, KD," Randolph said with a smile. "I appreciate that."

Before this year, Randolph hadn't made the playoffs since his second year in the league with Portland in 2003 and — like the Grizzlies — had never won a postseason series before.

All that is changing now for Randolph, an All-Star choice last season who was left out of the showcase this year.

"I've felt like I don't get a lot of respect I deserve. It's nothing personal or nothing," Randolph said. "I just try to come out and be the same player, consistent during the regular season and during playoffs. I just try to be this way all the time, play my way all the time, and not be up and down.

"The good players be consistent and stay consistent, not just playoffs but during the regular season, also."

The only player in the league to average at least 20 points and 10 rebounds each of the last three seasons, Randolph teams with Gasol to make the Grizzlies the NBA's most productive team in the paint with a 51.5-point average.

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The Grizzlies racked up 52 against the Thunder, who had bolstered their interior defense with their trade deadline pickup of Kendrick Perkins from Boston.

That move allowed Serge Ibaka — the league's top shot blocker — to move from center to power forward and give Oklahoma City two top defenders inside.

"They're not an easy matchup," Gasol said. "They're big and strong, kind of how we are. But we've got different ways to play. We don't just throw the ball in there and try to bang, bang."

Randolph started out with short jumpers to give Memphis the lead for good in the opening 2 minutes, then he followed a 17-5 run fueled by the bench with the Grizzlies' lone first-half 3-pointer to make it answer Durant's two-handed alley-oop and make it 54-38 with 2:26 left before halftime.

The Thunder used a 20-7 charge that spanned intermission to get back within 61-58 before Randolph steadied the Grizzlies again. He hit two free throws, a putback, a tip-in and then a jumper that caromed high off the rim before going in during a key stretch to keep Oklahoma City at bay.