Manchester United youngsters Facundo Pellistri, Ethan Laird, Anthony Elanga, Shola Shoretire and Will Fish trained with the first team on Sunday.
The five young players, all regulars in Neil Wood's United Under-23 side this season, were all called into Ole Gunnar Solskjaer's squad as United prepare to face Wolves on Tuesday night.
United's starters at Leicester were absent from on-pitch training images and are understood to have had a recovery session on Sunday due to the tight turnaround between matches.
Wolves is United's fourth game in just nine days and the first of four consecutive home fixtures, with Aston Villa due on New Year's Day before the Carabao Cup semi-final with Manchester City on January 6. Watford visit Old Trafford in the FA Cup third round on January 9.
Solskjaer is expected to rotate his side again for the home clash against Nuno Espirito Santo's side, after the trip to Leicester on Boxing Day. Daniel James and Eric Bailly were among the surprise starters at the King Power Stadium as United drew 2-2 thanks to Bruno Fernandes and Marcus Rashford goals.
Aaron Wan-Bissaka missed the Leicester game and the Carabao Cup victory over Everton before Christmas but was back in training on Sunday.
He was joined by 18-year-old Uruguayan winger Pellistri, versatile forward Elanga, centre-back Fish and 16-year-old attacking prospect Shoretire on the training pitches at Carrington. All five have put in a number of impressive performances for United's Under-23s this season.
United are likely to make changes as they face Wolves in the Premier League. They remain five points off leaders Liverpool with a game in hand.
