Amad Diallo impressed on his Manchester United debut after opening the scoring in the first leg. Diallo came on at half time for Anthony Martial and scored just five minutes later with a back header from 10 yards out.
Simon Kjær left United disappointed though when he scored in the 92nd minute. Ole Gunnar Solskjær's side now have to score to stay in the Europa League.
1-1 is the only score that could take the game to extra time and penalties.
David De Gea, Donny van de Beek and Paul Pogba are all available for selection and are making the trip to the San Siro.
Edinson Cavani suffered a reaction in the final training session before boarding the flight at Manchester Airport, according to Manchester United's Official Website. Eric Bailly will also miss the trip and will being assessed alongside the Uruguayan.
Anthony Martial also remains sidelined, potentially opening an opportunity for Mason Greenwood, Daniel James or Diallo. Juan Mata and Phil Jones both remain unavailable. Shola Shoretire is also not making the trip to Italy.
According to the Manchester United Official Wesbite, Zlatan Ibrahimovic can return and is fit for the match against his old club after announcing he is coming out of international retirement to play for Sweden in the next international break. Ismael Bennacer is also available but Ante Rebic, Alessio Romagnoli, Davide Calabria and Rafael Leao all miss out.
Hakan Calhanoglu and Theo Hernandez missed the first leg at Old Trafford but are back for the game in Italy.
Mario Mandzukic appears to still be on the sidelines while Diogo Dalot is eligible to feature again, despite being on loan from United.
Manchester United: Henderson; Wan-Bissaka, Maguire, Bailly, Telles; Fred, McTominay; Greenwood, Fernandes, James; Rashford.
AC Milan: Donnarumma; Dalot, Tomori, Kjaer, Hernandez; Kessie, Meite; Saelemaekers, Calhanoglu, Krunic; Castillejo.
Ones to watch
Ibrahimovic could come back to break Manchester United fans hearts as he is declared fit to face his former side. The Swede has played 14 and scored 14 in the Serie A this season, and at 39-years-old he is returning to international football after retiring back in 2016. The striker does not seem to be slowing down and United know just how dangerous he is. However, it is likely that he won't play the full 90 minutes.
For the Red Devils, Bruno Fernandes remains their star man, with 16 goals and 10 assists in the Premier League this season. The midfielder didn't have a big say in the first leg, however Fernandes will play a big factor in Thursday nights game. The chances are The Reds will continue to counter attack, but will try and get an early goal to cancel out Milan's away goal. Amad also deserves a mention after scoring United's only goal in the reverse fixture. The youngster is continuing to excite fans and will be hoping to see him feature again this week.
How to watch and kick off time
The match is set to kick off on Thursday evening (18/03/20) at 20:00 (BST). It will be available to watch live on BT Sport.