The victory was a welcome one for manager David Moyes, but although it was United's fifth win in six Premier League games, questions remain about their ability to revive their season sufficiently to challenge for the title.

They lacked creativity for the opening 45 minutes, when Swansea had the bulk of the possession, but the Welsh club failed to deal with the threat from Adnan Januzaj, who was involved in both goals.

Danny Welbeck scored their second one and has now hit the target six times in six games, while Antonio Valencia was also on target at the start of the second half.

Until then, Swansea had coped capably with the threat from United, despite having to reshape their side after only 17 minutes when Chico Flores came on for the injured Jose Canas.

Swansea, who dumped United out of the FA Cup last weekend, were already without several key players because of injuries, but they still created chances in the early stages.

A fifth-minute shot from Jonjo Shelvey was comfortably saved by United goalkeeper David De Gea, before a slick exchange of passes set up Wayne Routledge, whose poor first touch deprived him of a chance to shoot.

Moyes's team were slightly more incisive and could have gone ahead in the sixth minute when Nemanja Vidic hooked a shot over the crossbar after Swansea failed to deal with a corner.

Januzaj was also inches away from giving United a 11th-minute lead when his 20-yard free-kick dipped over the wall, but struck the bar.

Patrice Evra forced Swansea goalkeeper Gerhard Tremmel to make a routine save in the 28th minute, but United were far from convincing as they were stifled for long periods by their opponents' midfield.

Within 30 minutes, there were already rumblings of discontent from supporters who have grown accustomed to witnessing United overcome teams such as Swansea, who had won only one of their previous seven league games.

Their mood was not improved by Welbeck's failure to convert a 36th-minute chance that he dragged wide at the climax of their best move during a half in which Swansea enjoyed 66 percent of possession.

However, the atmosphere within Old Trafford was transformed after only a minute of the second half when Januzaj's movement down the left flank created a a goal that the match -- and United -- desperately needed.

He engineered space for a cross that reached Shinji Kagawa, whose header was saved by Tremmel before Valencia drove in the loose ball.

It was the catalyst for an impressive spell by United, who stretched their lead in the 59th minute.

Januzaj was again heavily involved when he won the ball in midfield and delivered a cross that was half-cleared to Patrice Evra.

The full-back's shot lacked power or accuracy, but Welbeck got a clever touch that turned it inside the right-hand post.

The traffic was now one-way in the direction of the Swansea goal.

United's earlier uncertainty had vanished and they should have added a third goal when Chris Smalling shot over the bar from only three yards out.

Kagawa also wasted a glorious opportunity when he delayed his shot in the 76th minute and Swansea were able to clear, but it hardly mattered.

The threat from the Welsh club proved to be minimal and, ultimately, this was a comfortable victory for United, who closed to within nine points of leaders Chelsea, their next opponents.