Arsene Wenger got the better of managerial rival Jose Mourinho for the first time in a competitive game as Arsenal beat Manchester United 2-0 in the Premier League on Sunday to keep alive its Champions League qualification hopes.Granit Xhaka and former United player Danny Welbeck scored goals in a four-minute span early in the second half to end United’s 25-match unbeaten in the league dating to October.This was the 16th competitive head to head between Wenger and Mourinho — and the 13th in league play — since 2004. It has been a one-sided rivalry but Wenger finally got a victory over the man who once dubbed him a “specialist in failure,” for a result that might end United’s chances of a top-four finish and leaves Arsenal with some hope.Arsenal is seven points behind third-placed Liverpool with two games in hand, and six behind fourth-placed Manchester City with one game in hand. Wenger’s team has four matches remaining to earn a 20th straight season in the Champions League.A disappointing game burst into life in the 54th when Xhaka, afforded plenty of space following a throw-in, advanced and sent in a 30-meter (yard) shot that struck the back of Ander Herrera and looped over goalkeeper David de Gea.Welbeck, who was sold to Arsenal in 2014 to end a 13-year association with United, has now scored in each of his last three appearances against his old club after powering a header in off the bar in the 57th from Alex Oxlade-Chamberlain’s cross.advertisementMourinho made eight changes to his starting team from the 1-0 win over Celta Vigo in the first leg of the Europa League semifinals on Thursday. The second leg is at Old Trafford on Thursday and Mourinho has suggested the European competition, which offers a place in the Champions League for the winner, is his priority for the remainder of the season.It meant the 19-year-old Axel Tuanzebe was handed his Premier League debut, at right back up against Alexis Sanchez, and he performed excellently. Scott McTominay, a 20-year-old midfielder, came on as a second-half substitute for his first-team debut while Paul Pogba — the world’s most expensive player — didn’t even come off the bench.Arsenal will climb above United into fifth place with a win at Southampton on Wednesday.