Sir Alex Ferguson gave credit to his defence after Manchester United's 1-0 victory over Swansea, but man-of-the-match Ryan Giggs warned his team-mates they must improve if they are to defend their Premier League title.

United looked set to coast to victory when Giggs set up Javier Hernandez for the opening goal in the 11th minute, but that proved to be the only goal as Swansea put the champions through one or two nervy moments.

Scott Sinclair should certainly have equalised when he missed an open goal in the first half at the Liberty Stadium, but United largely defended well and have now kept the most clean sheets in the Premier League. After their recent 6-1 defeat to neighbours City, that is significant improvement for Ferguson.

"Swansea have got a great home record and it's something we thought about before the game, it meant we had to defend well and we did that other than the miss they had in the first half," the United boss told ESPN.

"Other than I thought we were comfortable defending, but they're a good football team, they keep the ball well, and the concentration we showed today is exactly the type of concentration we need back in the team because a few weeks ago there was a genuine criticism of our defending.

"Apart from that one miss we were comfortable. We should have done better with a few chances on the counter, particularly when Chicharito squared for Wayne [Rooney], but in the context of form it was a good result."

Ferguson continued: "We've had a wake-up call. Over the years [defending] has been an integral part of our success. Michael Carrick, for instance, was magnificent today - that was a big, big performance from Michael. Darren Fletcher and Antonio Valencia both also did very well and it's important I can make changes at this time."

Giggs, making only his second league start of the campaign, set up the winner after intercepting Angel Rangel's pass, but he clearly was not happy with United's performance.

"Sometimes you get an early goal and tend to sit back," Giggs summarised. "We shouldn't have done that really. We need to play better if we're going to get positive results."