Declan Rice saluted "another incredible night for our academy" after a much-changed West Ham stormed to a 3-0 victory over FCSB in the Europa Conference League.
The Hammers became the first side to progress from the group stage with a 100 per cent record, thanks to Pablo Fornal's double and a Joyskim Dawa own goal.
With qualification already secured, David Moyes handed starting debuts to youth graduates Oliver Scarles and Divin Mubama, who played a crucial role before the own goal, while Kaelan Casey and Kamarai Swyer also made their senior bows from the bench.
Club captain Rice, who himself came through the Hammers' renowned youth system, was left out of the matchday squad, but posted on social media: "Another incredible night for our Academy."
Meanwhile, Moyes heaped praise on his young side, particularly the starting duo of Scarles and Mubama.
"Hopefully, we are getting future pressure on the boys in the first team," he told BT Sport. "All the boys played really well. We could have scored more goals.
"I thought Oliver Scarles played exceptionally well. Divin got a goal; I know it is being classed as an own goal, but he is a young centre forward, and you could see how much it meant for him to score.
"They have a great spirit in the Under-23s. There is a great spirit at West Ham and everyone is pleased for these young players.
"Everybody wants an opportunity, you just hope they can grab it and I thought both of them did tonight."