Swans captain Williams picked up an ankle ligament injury in the 2-2 draw with Liverpool and has played just once in the intervening period, against Crystal Palace.
The Group A meeting with St Gallen will be the third game in a row that the Wales captain has missed, and he is very unlikely to feature against Southampton prior to the international break.
Coleman, who names his Wales squad on Thursday, will desperately want to include Williams in his team to play Macedonia and Belgium, with his position under scrutiny with the nation bottom of their World Cup qualifying group.
But Laudrup has urged the Dragons boss to put Williams' long-term fitness first, as he believes he is doing himself, although he has yet to speak to Coleman on the matter.
The Dane said: "We have not spoken, I haven't had time. Let's see what happens in the next few days and what we decide for Sunday.
"If Ashley is playing or not, I am saying he should still go with Wales so the medical staff can look at him and then do the best for one person, for Ashley - not Swansea or the national side.
"Because as a player if you know you are not 100 per cent, it's bad. If there are things you can't do because of injury it's not good and, at this level, if that's the case your levels will drop.
"I've spoken to Chris a couple of times previously. We all agree the most important thing is the player.
"It's the same for us. I could say if we win against St Gallen we move on to six points and are top of group. We also want to win at Southampton on Sunday, so they are two important games for us.
Source: PA
Source: PA