Youngster Marcus Rashford will start up front for United after Martial's hamstring injury, following 'appearances' as an unused substitute for the Premier League games against Watford and Leicester earlier in the season.
The situation is eerily similar to the warmup in the tie's first leg last week, when David de Gea was ruled out at a similarly late stage in Denmark.
Sergio Romero came in as his replacement in that match, putting in a solid performance which was not enough to stop United sliding to a 2-1 defeat in the match, leaving them needing a win in tonight's game.
Both Wayne Rooney and Will Keane are already sidelined with injuries - Martial becoming the 14th player unavailable for Louis van Gaal.
What a bad luck for Van Gaal this season.
Speedy recovery Martial.