Youngsters go down 3-0 to League Two side.
Sunderland's development squad slipped to a 3-0 defeat at York in a pre-season friendly.
Coach Kevin Ball named a young side against a strong, experienced York team who are preparing for life back in League Two after winning promotion last time around.
All three goals were scored early on to give Sunderland a mountain to climb with the second half proving goalless.
The visitors did carve out a couple of chances but couldn't break through as they followed up last week's 4-3 reverse at Gateshead.
Ball said afterwards: "If we had been playing York's reserves I would have been very disappointed, but it was their first team.
"It was a fantastic test for us and I wanted the players to experience a game against league opposition.
"York could have come to play us up at the Academy, no problem, but I pushed to play at their stadium.
"I wanted the players to experience that type of football against league opposition, and ultimately if they want to play in our first team then they have to understand what I call the bread and butter side of things, where people really are playing for their living.
"I think the game brought home a few home truths for some of the boys and they have a lot of work to do.
"Once the season gets under way I want to see us playing against more teams like that - teams that are going to push the players because I want to see what they're all about.
"I want to see those who are prepared to challenge themselves and say 'I'll have a go'. They might still lose, but I want them to get that experience."