The 20-time English champions are in a strong position to reach the quarter-finals of the competition due to their 4-1 success in the first leg of the contest at Old Trafford.
Brazilian attacker Antony was unable to train with the Red Devils on Wednesday morning due to illness, and he has therefore been left out of the squad for Thursday's encounter.
Alejandro Garnacho is also absent, with the youngster picking up an ankle injury during Sunday's goalless draw with Southampton in the Premier League.
Anthony Martial is making progress in his recovery from a hip injury, but the Frenchman misses out once again alongside Christian Eriksen (ankle) and Donny van de Beek (knee).
However, there is positive news on the injury front, with Marcel Sabitzer able to return to the squad after missing the team's last two matches through injury.
Victor Lindelof has also returned to the squad after recovering from illness.
Casemiro is preparing to start a four-game domestic ban following his red card against Southampton, which will include this weekend's FA Cup quarter-final with Fulham.
However, the Brazil international is eligible to play in the Europa League and therefore makes the trip to Seville.
Nathan Bishop, Zidane Iqbal and Kobbie Mainoo were training with the first team on Wednesday morning, but the trio are not in the squad for the European clash.
Ten Hag is believed to be considering shuffling his pack due to Man United's strong position in the tie, with the Dutchman having one eye on Sunday's FA Cup last-eight contest.
Marcus Rashford, Jadon Sancho and Wout Weghorst are options in the final third of the field, while Anthony Elanga and Facundo Pellistri have also made the trip.
Despite having injuries in midfield and attack, Man United are currently well-stocked at the back, and club captain Harry Maguire will be bidding to secure a rare start against the La Liga outfit.
Man United squad vs. Real Betis:
De Gea, Heaton, Butland; Dalot, Lindelof, Maguire, Malacia, Martinez, Shaw, Varane, Wan-Bissaka; Casemiro, Fernandes, Fred, McTominay, Sabitzer; Elanga, Pellistri, Rashford, Sancho, Weghorst