LONDON (REUTERS) - A defiant Manchester United manager Louis van Gaal has answered critics of his side's performances by pointing out that his team would be top of the Premier League based on their form since November.

The Dutchman has come under scrutiny as United have put on a string of uncharacteristically subdued displays since taking over at Old Trafford, often relying on excellent goalkeeper David de Gea and snatching goals against the run of play to carve out results.

Van Gaal, who has tinkered with different formations and resorted to playing striker Wayne Rooney in central midfield, defended the team's lack of attacking verve by highlighting the results over the last four months.

"When you see the score of the last 19 or 20 matches, we are the best team in the league," he told a news conference on Friday ahead of his side's visit to Swansea City on Saturday.

"I am never 100 per cent (happy). We can play better than we are now, but the main thing is to win games. We've shown our team spirit many times this season. It's good for the fans and for me, as you see a player wants to follow you."

United are third in the standings on 47 points, 12 adrift of leaders Chelsea, but have taken more points (34) from their previous 15 league matches than any other Premier League side and have lost just once in 19 games in all competitions.

They booked an FA Cup home quarter-final against holders Arsenal with a 3-1 win at Preston North End on Monday.

In that match, van Gaal had to change the formation and personnel after the 20-time English champions fell behind against their third-tier opponents.

"I believe that every player knows the philosophy of me and my staff and everyone wants to follow that philosophy," he said. "Our team spirit is unbelievable.

"When we change the system during the game we always surprise our opponent and that's why it's also a good thing for our team. Of course, it is not always that we improve our game but mostly we have improved and won the match, so that's important."