James Harden admitted he "was just doing everything that was not supposed to happen" before coming up with a vital series-winning block in Game 7 against the Oklahoma City Thunder.

Houston Rockets superstar Harden had just 17 points on Wednesday after also failing to have an impact late in Game 6.

The Thunder won on that occasion as Russell Westbrook was instead handed control of the team down the stretch and contributed costly clutch errors, prompting Chris Paul - Harden's ex-team-mate - to say: "Some people are built for it, some people shy away from it."

But just as it looked as though Harden would come up short again, a block on Lu Dort denied the OKC rookie the chance to win the first-round series from three-point range in the closing seconds.

"Physically, I felt like s*** - excuse my language," Harden told ESPN. "I couldn't make a shot, turned the ball over, was just doing everything that was not supposed to happen, but I just kept sticking with it.

"My team-mates give me confidence throughout the game. Defensively I had to make a play and I closed it out to him. Dort has been making some shots, so I wanted to get out to him."

Harden's defensive game has often been criticised but he said he had "been locked in all year long trying to be better" and "tried to find a way to impact the game".

For that reason, he ranked the play - with his team 103-102 ahead - among the best of his outstanding NBA career.

"It's one of the top ones, definitely," Harden, who reacted with a roar of delight, said afterwards to reporters.

"It's cool to get 40 or 50 points, shooting the ball, shooting the ball - obviously we all want to do that - but just to get recognition and for it to pay off when it counts on the defensive end, showing that I've been engaged and locked in, means a lot."

The final play was harsh on Dort, who went undrafted last year, only debuted in December and averaged just 6.8 points in the regular season but came up with a game-high 30 in the decider.

The 21-year-old made six three-pointers but could not find a way past Harden at the last and threw the ball out of bounds when his shot was blocked.

"I just kept my confidence. The way they were playing me, they were letting me shoot," Dort said. "Even though I had a couple of bad nights, I stepped up and shot it with confidence.

"On the last one, I just didn't think he was that close but he was and he got it. It felt good and I was confident enough to take that shot, but he was just there and it was a good play from him."

Harden said of his opponent: "I've known him since college, when I would go back to Arizona State, and he would work his butt off. It's showing.

"He played extremely well tonight; on the offensive end, he made a lot of shots. He just plays his butt off. He doesn't care about anything but playing hard.

"As a young guy, coming into this league, that's all you can ask for. Learning how to play and learning defensive schemes and offensive schemes, the total package of being an NBA player, that is going to come.

"But he has the right mindset of just playing hard and not caring what anybody thinks. He's going to have a great career."