Ole Gunnar Solskjaer has changed his entire Manchester United XI for the trip to Astana, naming seven teenagers from the start in the Europa League.
United drew 3-3 at Sheffield United on Sunday, but none of the players in the line-up at Bramall Lane even made the matchday squad on Thursday.
Ethan Laird, 18, Di'Shon Bernard, 19, and Dylan Levitt, 19, were all handed full senior debuts as expected.
United have also called on James Garner, 18, Tahith Chong, 19, Angel Gomes, 19, and Mason Greenwood, 18.
Axel Tuanzebe, stand-in captain Jesse Lingard and Greenwood all came off the bench against Sheffield United and are promoted into the starting XI, while Luke Shaw plays for the first time since August.
The Red Devils have not named as many teenagers in an XI since Opta records began.
The next-most saw five United players under the age of 20 in the team against Burton Albion in the EFL Cup in 2005.
With an average age of 22 years and 26 days, United's team is the youngest they have ever named for a match in major European competition, excluding qualifiers.
As Solskjaer revealed earlier in the week, there would be further debuts from the bench, with each of the seven substitutes academy players.
Max Taylor was among them a little over a year after he was diagnosed with testicular cancer.
"I think [it's exciting]," Solskjaer told MUTV. "I enjoyed training yesterday, I've enjoyed the trip with them.
"It's a group that has been together for a long time, so they know each other. For them, it's the next step really, but with some experience - Axel, Jesse, Lee, Luke - with them.
"For the kids, it's a great occasion. We struggle to give them enough games against men. Today, we are playing against men.
"[Astana are] an experienced team, a physical team, in front of 30,000 people. It's a great education for them."
United have already secured their place in the Europa League last 32 but can clinch top spot in Group L if they win and AZ, playing Partizan Belgrade, do not.