United's defence was expected to be their weak point this season, but they have not conceded in their first three Premier League matches.
That may change on Sunday when they visit the Liberty Stadium, however.
Swansea have devastating pace on both flanks, courtesy of Andre Ayew and Jefferson Montero, while Bafetimbi Gomis has bagged three goals in three games up front.
"Swansea are a very good team," said the United manager, who lost twice to Garry Monk's men last term.
"They play a positional game like we do
They want to build up and have a good attack with speed and creativity.
"They proved they are a good team this season in the draw against Chelsea and against Newcastle, and when I see the individual players I see that they have quality.
"You spoke about Montero but they also have Ayew, Gomis and (Gylfi) Sigurdsson who have creativity
They are a difficult team to beat, especially away."
After tour wins over Real Madrid, Liverpool and Inter Milan, Swansea brought Van Gaal back down to earth by winning at Old Trafford on the opening day of last season.
The Welsh side then completed their first league double over United with a 2-1 victory in Swansea in February.
Van Gaal admits he could not stomach a third defeat to Monk's side.
"I don't want to lose again," Van Gaal told MUTV.
"It's the only club we could not beat or gain one point against [last season].
"It's a difficult team against us and before my period it was also difficult for United, so I hope we can improve and that we can show that we are better than last year."
United warmed up for the match in the best possible fashion by hammering Club Brugge 4-0 in the Champions League on Wednesday.
Wayne Rooney scored a hat-trick and Ander Herrera chipped in with another goal as United sealed their progression to the Champions League group stages with a 7-1 aggregate win.
Juan Mata was impressed by the performance but knows success in the Premier League is just as important to the club as European glory.
"The Champions League is the best competition to play in," the United playmaker said.
"I've been lucky enough to win it once and it's amazing
Last season it was difficult to watch the games; now we have the chance to enjoy it.
"But while we are happy about that, it's now time to think about the next game on Sunday
From now on we want to win every game in the Premier League."
Mata's week got even better on Friday when he was recalled to the Spain squad for the upcoming Euro 2016 qualifiers with Slovakia and Macedonia.
"I am very happy," he said.
"It's amazing to play for your country
I have done it many times but it's been a while since the last time so I am very happy and proud.
"We have important games for the European Championships
We have Slovakia, the team leading the group, and Macedonia so it will be tough, but we are looking forward to it."
Mata is almost certain to keep his place in the starting XI for Sunday's game in Swansea.
Adnan Januzaj and Phil Jones are both out through injury, but Marouane Fellaini is available following a three-match domestic suspension.
Source : PA
Source: PA