Swansea City 2 Manchester United 1

Louis van Gaal must be sick of the sight of Swansea City. The Dutchman has been managing in the Premier League for little more than a year but he has now suffered three straight defeats at the hands of the Welsh club, with the latest bringing home what a terrible mess Manchester United have got into with their goalkeeping situation.

It was not much of a way for Van Gaal to celebrate his 50th game in charge of United as Sergio Romero, who looked unconvincing all afternoon, allowed Bafétimbi Gomis's low shot to slip past him at the near post. Romero could arguably have done better with Swansea's equaliser five minutes earlier, when the irrepressible André Ayew beat him with a downward header.

It was some response from Swansea, who had fallen behind three minutes into the second half, when Juan Mata turned home Luke Shaw's cross. Ayew already looks like one of the best pieces of business done this summer. He has now scored three in four games, but it was the gorgeous pass that released Gomis for Swansea's second that provided the highlight of the game. Gomis is also enjoying himself and now has nine in his past 10 Swansea appearances, including four in four this season.

As for United, on the back of their thumping Champions League qualification victory over Club Brugge in midweek it was hard to view this as anything other than a reality check, in particular for Wayne Rooney, who endured a torrid afternoon that was summed up by the gilt-edged chance he created, and then squandered, to bring the visitors level in the closing minutes.

Few teams come to the Liberty Stadium and dominate possession but United, with Bastian Schweinsteiger operating alongside Morgan Schneiderlin in front of the back four and Ander Herrera playing in the No10 role, took control of the game early on, monopolising the ball and denying Swansea the chance to impose their own passing game.

It was one-way traffic in the opening 20 minutes but United, not for the first time this season, lacked a cutting edge. Memphis Depay’s whipped free-kick forced Lukasz Fabiankski into a hurried save inside the first two minutes and Mata, after some dextrous footwork from Herrera, dragged a left-footed shot wide of the near post later.

Rooney had United's best chance of the first half two minutes earlier, when Luke Shaw's measured pass released him in the inside left channel. The United captain lacked conviction, however, and his indecision allowed Ashley Williams to get back and nick the ball off him. Later in the half, Rooney found himself in a similar position when he ran on to a ball from Herrera only to shoot tamely at Fabianski.

After their slow opening, Swansea came back into the game midway through the first half and ought to have taken the lead after creating two excellent chances. Following a well-worked free-kick involving Jonjo Shelvey and Gomis, Gylfi Sigurdsson steered his right-footed shot from eight yards agonisingly past the far post with the United defence exposed.

Playing with renewed confidence, Swansea came back for more and only the width of the post denied Gomis the breakthrough goal. Running on to Shelvey’s pass, the Frenchman turned Daley Blind far too easily and, after taking another touch to open up the chance for a shot, stabbed the ball against the upright.

It was United, though, who took the lead and it was a soft goal to concede from Swansea’s point of view. Credit to Shaw for his driving run on the left, but Kyle Naughton’s challenge on the United left-back was weak and Williams was caught sleeping when a floated cross from the England international found its way to the far post. Mata ghosted in and swept United ahead.

Garry Monk responded by withdrawing Wayne Routledge, who started in place of the injured Jefferson Montero, bringing on Ki Sung-yueng and changing from 4-2-3-1 to a midfield diamond, with Ayew joining Gomis further forward. Three minutes later the Swansea manager had his reward.

Williams, keen to atone for his part in Mata’s goal, carried the ball forward from deep inside his own half, after Rooney had squandered possession, and picked out Sigurdsson wide on the right. With the time to look up and pick out a man, the Icelander delivered an inviting cross that Ayew, unmarked after running off the back of Schneiderlin, headed into the ground and past Romero.

The momentum of the game had shifted and in the blink of an eye Swansea were in front. Shelvey and Sigurdsson were involved in the buildup, but it was a majestic pass from Ayew with the outside of the left boot that carved open the United defence and invited Gomis to run behind Chris Smalling. The angle was tight as Gomis struck a right-footed shot goalbound, and only Romero knows how he allowed the ball to squeeze inside his near post.