And last night Van Gaal revealed the timescale for the left-back's recovery.
"I am not a doctor so I cannot say that, but when you have a double fracture it is I think until six months," Van Gaal said.
Southampton V Manchester United - Premier League Preview
"It is about how it develops. You can never say that in advance.
"He will not play in the group phase I think. I hope he can play again this season."
Shaw endured an injury-plagued start to his United career when he joined the club from Southampton in a £27million transfer last summer.
The England international injured his hamstring in August 2014 and was out for a month - only to return and pick up another knock in a clash with Arsenal that kept him sidelined for a further six weeks.
We use your sign-up to provide content in ways you've consented to and to improve our understanding of you. This may include adverts from us and 3rd parties based on our understanding. You can unsubscribe at any time. Read our Privacy Policy