Diego Gomez made his first start in Albion colours – as he had a run out with the under-21s.
The Paraguay midfielder played the first half of the Premier League 2 fixture against Manchester United at Lancing.
The young Seagulls went down 1-0, beaten by a fifth-minute penalty.
Ruari McConville also played the first 45 minutes.
Both he and Gomez were unused subs for the seniors as they lost to Everton on Saturday.
Gomez is adapting to life and football in England after his winter switch from Inter Miami.
He made a very brief Premier League debut at Old Trafford last Sunday.
Minutes with the development squad is in line with what happened his South American midfield predecessor Moises Caicedo.
First team boss Fabian Hurzeler expects Gomez to be a success in the Prem.
Speaking ahead of the Everton game, Hurzeler said: “He gives the team something what we don't have. So he has a special profile.
“I would say he's a warrior on the pitch. He can run a lot. He can fight a lot. He makes the last step in personal duels.
“It's about giving him the understanding of our style of play. It's something completely different for him. You can feel it in every training session that he tries to listen, that he tries to adapt.
“He's learning English. That's something very positive, but I think we shouldn't force it.
“We need to give him game time for sure, so that he can integrate as quick as possible, but also give him time so that he adapts to the intensity, that he adapts to the new culture.
“But the first weeks with him, I really enjoyed working with him. He's a player who pushes his limit.
“He's a player who always wants to give more than 100 percent and that's a profile I really like.”
