Both sides met during the league phase earlier this season, with Midtjylland emerging 3-2 winners, but Nottingham Forest now have another opportunity for revenge.
Atlético opened the scoring through centre-back Robin Le Normand, who headed home from a Giuliano Simeone assist, making it his second goal of the season.
Benitez’s coaching career has spanned other top clubs in Europe, including Real Madrid, Everton, Newcastle United, Inter Milan, and Valencia, among others.
“I want to make it clear that representing my nation is an honour.’’
The club said further tests would be carried out on Wednesday to ascertain the full extent of the injury.
Diego Simeone’s men beat Celta Vigo 4-1 on Saturday in their first home win of the season.
