PORTLAND, Oregon — Stephen Curry had 37 points before sitting out the final quarter as the Golden State Warriors welcomed back teammate Kevin Durant with a 128-103 victory over the Portland Trail Blazers on Monday night to sweep their first-round playoff series. The Warriors advanced to the conference semifinals, where they’ll face the winner of the series between the Utah Jazz and the Los Angeles Clippers, which is tied at 2. Golden State played for the second straight game without coach Steve Kerr, who has been experiencing a flare-up of symptoms stemming from back surgery a couple of years ago. Assistant Mike Brown has served as head coach in Kerr’s absence. Durant hadn’t played since Game 1 because of a strained left calf. He started and the Warriors built a 72-48 lead by the end of the opening half. Golden State pushed the margin to 33 points in the second half. Curry swished a 31-foot 3-pointer that made it 104-77 late in the third quarter and the Blazers couldn’t catch up. Durant finished with 10 points in 21 minutes. All of Golden State’s starters were in double figures. Damian Lillard scored 34 points for the Blazers, who were making their fourth straight appearance in the playoffs. The Warriors jumped out to a 14-0 lead at the start. Durant’s dunk extended the lead to 22-3 and the rout was on. JaVale McGee made a highlight-reel alley-oop dunk in route to a 45-22 lead after the opening quarter. It was the most points ever in a quarter for Golden State in a playoff game, and matched the NBA record for most first-quarter points in a playoff game.