Steve Kerr insists the Golden State Warriors are going to "fight the whole way" after their hopes of a third successive NBA title suffered a severe blow on Friday.

Even with the return of Klay Thompson from injury, the Warriors fell to a 105-92 defeat in Game 4 of the Finals against the Toronto Raptors, who now require just one more win to secure a first championship in their history.

However, the Warriors know all too well that a 3-1 lead can be overturned, having been on the wrong end of a historic comeback by LeBron James' Cleveland Cavaliers in the 2016 Finals.

Kerr expects his players to show a reaction following back-to-back defeats on home court, with Game 5 taking place in Canada on Monday.

"We're not thinking about winning three games, we're thinking about winning one game and that's the task," the Warriors coach told the media.

"I know we're capable. We've got a lot of talent and we've got a lot of pride, and these guys have been to the Finals five straight years for a reason.

"They're unbelievably competitive. And they're together, and they're going to fight. They're going to fight the whole way.

"So we'll go try to get one win and, if we can do that, come back here and see what happens."

The Warriors held a narrow lead at half-time but Toronto produced a stunning third quarter, outscoring their opponents 37-21 to seize control.

Kerr was quick to praise the Raptors, who were led by 36 points from three-time All Star Kawhi Leonard.

"We're playing a really good team that moves the ball. I think we have had our moments defensively, but we haven't been able to string together the stops over the course of a game that we have needed to," he said.

"I give them the credit. They have just played really well offensively, and they got a lot of threats out there, a lot of shooters, a lot of passers.

"So they're playing well, and we have got to do better."

Thompson had 28 points for the Warriors after missing Game 3 with a strained hamstring.