Louis van Gaal failed to find any instant fix for Manchester United's problems as his first Premier League game in charge ended in a 2-1 defeat by Swansea City at Old Trafford on Saturday. Gylfi Sigurdsson's 72nd minute winner for the visitors condemned United to their first opening day home top-flight loss for 42 years and laid bare the problems Dutchman Van Gaal has to restore the fortunes of the 20-times champions. Skipper Wayne Rooney drew United level after 53 minutes with an overhead flick and he curled a free kick against the post soon after but Swansea were largely untroubled. United had plenty of first half possession but lacked invention and pace and Swansea took the lead with their first real attack when Ki Sung-yueng slotted home after 28 minutes. There was more thrust about United immediately after the interval and they equalised when Phil Jones flicked on a corner and Rooney, with his back turned away from goal, cleverly hooked the ball past Swans keeper Lukasz Fabianski. Van Gaal's expression barely changed in the dugout, but the mood in the stadium did lift as United threatened and Rooney sent a curling free kick around the wall and off the woodwork. However, United lacked fluency and always looked vulnerable to the counter-attack. Swansea manager Gary Monk sent on substitute Jefferson Montero for his debut and the Ecuadorian made an instant impact, sending in a cross to the far post which caught United left back Ashley Young out of position. Wayne Routledge scuffed a shot across goal and Sigurdsson, back at Swansea after moving from Tottenham Hotspur, made no mistake from the just outside the six-yard area. "I think the shape and the way we defended was key. The manager set us up perfectly. We showed character, dug in at the end and I think in the end we deserved it. We knew it would be difficult with a new manager to come in here," match-winner Sigurdsson told BT Sport. United's fans began drifting away well before the end as the hosts huffed and puffed to grab an equaliser, but apart from the occasional flurry, never looked like salvaging a point. Van Gaal left the pitch shaking hands with fans but the former Barcelona, Bayern Munich and Ajax coach knows he has a major task on his hands to get United challenging the top four after slumping to seventh last season.