Durant knew it would be different, but vowed to do whatever he could to carry his team through this difficult period.
He delivered on that promise by scoring 41 points and helping Oklahoma City fight off Houston's late rally to beat the Rockets 104-101 for a 3-0 lead in the best-of-seven playoff series.
"I didn't feel the same," Durant said. "And I knew I just had to give my all from here on out ... every game is for him."
Durant checked his phone moments after leaving the court and smiled recalling the text messages he received from Westbrook.
"He texted me at halftime and right after the game," Durant said. "Just said congrats and that he loved me."
Durant scored 27 points in the first half, and the Thunder led by 26 points before a big third-quarter rally by the Rockets put them within striking distance.
Houston regained the lead with about 4 minutes left, and was up with less than a minute remaining. But Durant hit a 3-pointer, which bounced off the rim before falling in, to put Oklahoma City on top 100-99.
"We didn't want to give up any 3s," Houston's James Harden said. "He just made a lucky shot. It was good defense. It just went in and took some of the energy out of us."
Houston had a last chance, but Carlos Delfino's 3-pointer fell short.
Thunder coach Scott Brooks was impressed that his team was able to win despite losing its All-Star point guard.
"It's been an emotional time the last 48 hours," Brooks said. "We all love what Russell (Westbrook) is about. He's got probably the biggest heart I've ever been around."
Fisher said it was difficult getting through these last couple of days, but the 16-year veteran said he was there to help the younger guys deal with the loss of Westbrook.
"We're still grieving, so to speak, as a team," Fisher said. "But that's why I'm here, and that's why this is a team. Injuries and bad things happen in sports, but we still have to figure out a way to get things done."
Harden scored 30 points for the Rockets in the first playoff game in Houston since 2009. The Rockets will be at home again for Game 4 on Monday night.
Westbrook was injured in Game 2 and had season-ending right knee surgery Saturday. It was the first time Durant had played a pro game without Westbrook, who hadn't missed a game in his career before Saturday.
Durant's 41 points equaled a playoff career high, and he also had 14 rebounds, four assists, two steals and a block. He sat down for just 44 seconds on Saturday.
"Kevin has done a great job of being a playmaker all season long," Brooks said. "He's an amazing scorer, and he sets up a lot of guys to get easy buckets."
Jackson made his first career start in place of Westbrook and had 14 points, and Serge Ibaka added 17 points and 11 rebounds.
Chandler Parsons had a tying 3-pointer for Houston with 5:46 left, and Delfino put the Rockets in front for the first time since early in the first quarter when he connected from long range to make it 94-93 about 2 minutes later.
Ibaka made four straight points after that, ending with a reverse layup, to make it 97-94 with about a minute and a half left.
Harden hit a pair of free throws. Then Francisco Garcia's 3-pointer put them up 99-97 with 45 seconds left, before the clutch shot by Durant.
The Rockets rallied from a 15-point deficit to take a lead in the fourth quarter in Game 2. But they weren't able to hold on and Oklahoma City got the 105-102 win.
It was much the same this time, as Houston went up late only to fall again.
"We've got to find a way to win those games," Houston coach Kevin McHale said.
Harden complained that he and his teammates were sluggish and lacked energy early. He knows that won't cut it if they expect to win on Monday.
"We have to have that energy from the beginning of the game to the end of the game," he said. "We can't have droughts. You have to play a solid game for 48 minutes."
Westbrook's absence didn't seem to bother Oklahoma City early, as Durant had the big first half and the Thunder looked to be in complete control.
Things changed in the third quarter when Durant was limited offensively and Houston outscored the Thunder 27-14 in the period.
Houston point guard Jeremy Lin, who bruised a chest muscle in Game 2, started but scored only two points in about 18 minutes.
Parsons scored 21 points, and Garcia had 18.
After a big run got Houston within eight in the third quarter, Garcia and Harden made 3-pointers around a dunk by Durant to whittle the lead to 80-76 entering the last quarter.
Durant was scoreless in the third until his dunk with 27 seconds remaining in the quarter.
The Thunder led by 19 points when the Rockets used a 16-5 surge to get to 78-70 with 2 1/2 minutes left in the third. The Rockets harassed Oklahoma City into three turnovers in that stretch, and Durant went cold as he missed four shots.
Garcia and McHale received technical fouls in the first quarter. ... Pitching great Roger Clemens and Houston Texans star receiver Andre Johnson attended the game.