OKLAHOMA CITY — Kevin Durant scored 24 points, Russell Westbrook made a run at a triple-double in three quarters and the Oklahoma City Thunder routed ex-teammate James Harden and the Houston Rockets 120-91 on Sunday night in Game 1 of their playoff series.After letting Houston wipe away an 11-point deficit in the first half, the Thunder regained control with a 14-1 surge just before halftime and kept pouring it on.Just after a fan nailed a half-court shot to win $20,000 in the break after the third quarter, Durant drove for a two-handed slam while getting fouled and Oklahoma City was soon up by 30.Harden, playing against the team that traded him away just before the season started, had 20 points but the league’s second-highest scoring offense was held 15 points below its regular-season average while shooting 36 percent.“We were trying to be solid on the defensive end,” Durant said. “We knew they were a great scoring team. We just tried to pack the paint and get out to their shooters. We had to make the second and third efforts, and I think we did that.”Game 2 is Wednesday night in Oklahoma City.The Thunder were already up by 23 when Larry Hill connected on the half-court shot and went bounding toward Oklahoma City’s huddle in celebration, getting congratulated by Thabo Sefolosha before the team’s bison mascot pulled him back away.Durant’s dunk sparked a string of seven straight points for Oklahoma City, and Harden never even came off the bench in the fourth quarter. Coach Scott Brooks called timeout and pulled Durant a few moments later, and reserves finished out the game for the Thunder.Westbrook ended up with 19 points, 10 assists and eight rebounds. Serge Ibaka chipped in 17 points and Kevin Martin, Harden’s replacement in the sixth man role, had nine of his 16 points in the fourth quarter with the game already in hand.It was an impressive playoff opener for top-seeded Oklahoma City, which made it to the NBA Finals last season before losing to Miami in five games.“We wanted to take care of our home court,” Durant said. “We didn’t do anything yet.”Harden didn’t get much help the rest of his starting lineup, with three of them making their first career playoff start. None of the other starters scored in double figures and the unit went 17 for 50 from the field, with Harden making just six of his 19 attempts.“We’re not looking at him as a friend right now,” Durant said before the game. “Of course, we all know him but it’s Rockets versus Thunder. We want to come out there and try to stop whoever they put out on the floor. It’s not about just James.”It was Houston’s first playoff appearance in four years.“This is a young team. This is a lot of guys’ first time in the playoffs,” coach Kevin McHale said beforehand. “Or even if they’re not in their first time in the playoffs, it’s the first time they’ve started a playoff game. This is the first time they’ve done a lot of stuff. For us, it’s a great experience. We’ve just got to get better.”Houston, which set a franchise record for 3-pointers during the regular season, finished 8 for 36 (22 percent) from behind the arc.Oklahoma City scored the first six points of the game and opened a 13-2 lead as the Rockets failed to make a basket for the first 6 minutes of the game and started out just 1 for 13 from the field. Houston eventually settled in and charged back with a 13-2 push spanning the break between the first two quarters, with Chandler Parsons providing the final five points on a two-handed putback jam and a 3-pointer.Patrick Beverley pulled the Rockets even at 38 with a transition 3-pointer from the right wing, but the Rockets couldn’t pull ahead before Oklahoma City’s next surge.Sefolosha had a two-handed slam on a fast break and also assisted on Kendrick Perkins’ two-handed dunk during the burst, which extended Oklahoma City’s lead to 60-45 before Harden’s driving layup in the final second before halftime.All but the first basket in the Thunder’s run came after Omer Asik joined Parsons on the bench with three fouls apiece.The Rockets never recovered.