PORTLAND, Ore. — The Golden State Warriors’ season has not been a straight line. They have coped with injuries, behind-the-scenes squabbles, fatigue and even complacency. But they are still a basketball superpower, and they are imposing their will this postseason with another majestic romp past overmatched opponents.

On Monday night, the Warriors clinched a fifth straight trip to the N.B.A. finals by completing a four-game sweep of the Portland Trail Blazers in the Western Conference finals. With their 119-117 overtime victory at the Moda Center, the Warriors also preserved their hopes of a third straight championship and their fourth in five seasons.

The only other team to reach five straight N.B.A. finals was the Boston Celtics, when they went to a record 10 in a row from 1957 to 1966 (and won nine titles, eight consecutively). The Los Angeles Lakers were the last team to three-peat as champions, from 2000 to 2002.

“I hope it doesn’t go unnoticed or underrated,” Warriors Coach Steve Kerr said. “Five straight finals hasn’t been done since the ’60s, since Bill Russell’s Celtics. And it hasn’t been done for a reason: It’s really, really difficult.”