Stephen Curry announced his return to the playoffs on Monday with a breathtaking performance that both revived a jaded-looking Golden State Warriors team and reinstalled them as clear favorites to defend their NBA title.

When Curry went down with a right knee sprain two weeks ago, it both cast doubt on Golden State's chances of repeating last year's championship triumph as well as severely reducing the entertainment value of the post-season.

However, the NBA's star man was fit enough to reclaim his place in the lineup in Portland and returned to action with a 40-point shooting exhibition that put Golden State back in the driver's seat in their Western Conference semi-final.

The Warriors outlasted the Trail Blazers 132-125 in overtime to seize a 3-1 lead in the best-of-seven series and Curry had a clear message for the league, which he shouted after one of his impossible three-pointers: "I'm back!"

"I just tried to give whatever energy I had to my team mates," Curry told reporters after scoring an NBA-record 17 points in overtime to cap a 37-minute comeback.

"It took a while to find a groove but I finally found it."

Some wondered whether Curry would find anything remotely like his groove again this season after he was injured in the first round against Houston on April 24.

His initial prognosis was that he would be re-evaluated after two weeks but there was no guarantee that he would return.

In his absence, Golden State finished off the Rockets and took a narrow lead over Portland but their playoff run lacked the skill and energy of their record 73-win regular season when Curry led the charge.

Eastern Conference top seeds Cleveland and West rivals San Antonio were suddenly poised to pounce on the now-vulnerable Warriors in the race for the Larry O'Brien Championship Trophy.

Golden State coach Steve Kerr had initially listed Curry as 'doubtful' in the days preceding Game Four against the Blazers but changed his tune and activated his point guard when he went through a successful warmup.

Curry came off the bench and the plan was to limit him to around 25 minutes, but that was thrown out the window when starting guard Shaun Livingston was ejected with two technical fouls in the second quarter.

"That put us in a tough spot, especially with Steph's comeback," Kerr said. "I don't think anyone could have predicted the explosion. That was crazy.

"The guy had played one basketball game in three weeks."

That single game, however, was all the reigning MVP appeared to need to restore basketball's balance of power back in Golden State's favor.

The Warriors can wrap up the series when they host Game Five in Oakland on Wednesday.