Anthony Martial's dream Premier League start continued as the £36m striker scored twice to lift Manchester United to second with a win at Southampton.

United started poorly and went behind when Graziano Pelle converted a loose ball after David De Gea's fine save.

But Martial equalised with United's first shot on target and then took advantage of a terrible Maya Yoshida backpass to slot in a second.

Juan Mata added a third and while Pelle headed a late second, United held on.

Louis van Gaal's side were given a torrid time by the Saints in the opening half an hour but were once again clinical in front of goal.

United scored with all three of their shots on target against Liverpool last weekend and repeated the trick at St Mary's as Southampton - who have now won just two of their last 12 league games - slipped to defeat.

Wayne Rooney's poor start to the season as the leading man in United's attack led to a first league start for £36m signing Martial.

Rooney - with no goals or assists in the Premier League - started behind Martial and produced a laboured and largely anonymous display.

He - and Martial - had barely seen the ball in the final third as Southampton started superbly, before the Frenchman put United level.

Mata was offside in the build-up but Martial - who scored on his debut against Liverpool last week - again showed composure to turn Virgil van Dijk and fire home.

Martial became the third player to score on both of his first two Premier League appearances for United, after Louis Saha in 2004 and Federico Macheda in 2009. He finished coolly for his second when played through on goal by Yoshida's blind backpass.