LONDON — Swansea City came from behind to end Manchester United's unbeaten start to the Premier League season with an impressive 2-1 victory at the Liberty Stadium Sunday. After an entertaining first half ended goalless Juan Mata fired Luke Shaw's teasing cross into the roof of the net in the 48th minute before Swansea took control. Andre Ayew restored parity with a headed effort 13 minutes later before Bafetimbi Gomis maintained his superb form with a low shot five minutes later as the Welsh side registered their third successive 2-1 league victory over United. "It was a very difficult game," Swansea captain Ashley Williams told Sky Sports. "We had to dig deep. "Any time you can beat one of the top teams shows our improvement. We keep working every day and every week. We want to be a consistently good side." Earlier, Dusan Tadic's brace and a goal from Graziano Pelle gave Southampton's stuttering league campaign lift-off with a comfortable 3-0 victory over promoted Norwich City at St Mary's. Norwich defender Steven Whittaker was sent off having received two yellow cards within four first-half minutes for professional fouls as the south-coast club registered its first victory of the season. United's solid yet unspectacular start to the season had been built on a steely defense which had yet to concede and had restricted opponents to just five shots on target in three matches this season. Swansea, however, achieved a Premier League double over United last season and had started the season unbeaten, including an impressive opening-day draw at champions Chelsea. United started brightly, though, with Memphis Depay and Mata sending early warnings of United's attacking threat. Swansea began to grow into the game having weathered United's early attacking raids with Gylfi Sigurdsson firing agonisingly wide before Bafetimbi Gomis curled an effort against the post. Wayne Rooney netted a midweek Champions League hat trick but continued his underwhelming domestic form, squandering a host of inviting chances and having fewer first-half touches than every other United player. After the break Mata fired in before the host turned the game on its head. Ayew headed home Sigurdsson's cross before the Ghanaian's stunning pass created space for Gomis to slide home his ninth goal in his last 10 Premier League matches. Swansea, Which has eight points from four games, leapfrogged United, with seven, into fourth. Southampton moved up to 10th with five points while Norwich sits one point adrift in 14th. Manchester City tops the standings going into the international break with a maximum 12 points from four games, three ahead of Crystal Palace. Roma beats Juventus Miralem Pjanic and newly signed Edin Dzeko scored in the second half as Roma beat title rival Juventus 2-1 Sunday, leaving the defending champion with two straight losses to start the season. Goalkeeper Gianluigi Buffon hardly moved when Pjanic placed his free kick perfectly over Juventus' wall and into the left corner in the 62nd minute Pjanic also hit the post midway through the first half. After Juventus fullback Patrice Evra was sent off for his second yellow card, Dzeko headed home from inside the box in the 79th for his first goal since joining Roma on loan from Manchester City. Paulo Dybala pulled one back for Juve in the 87th. Roma has three points, Juventus remains with none. — Agencies