The 19-year-old has previously sat on the bench during three Champions League matches for Manchester United.
But in tonight's match against Swiss Young Boys, the Swede is included from the start.
Elanga was replaced with a quarter left in this weekend's Premier League meeting when Manchester United hosted Crystal Palace.
It was the new coach Ralf Rangick's first match at the sideline since he took over from Ole Gunnar Solskjaer.
It was the first time this season the Swede was in the match squad during a Premier League match.
The match was won by United 1-0.
The match starts at 20:45.