Duncan Watmore missed a penalty but completed 57 minutes in a successful return to Sunderland action.
It was the 25-year-old's first competitive action since suffering an ACL injury last November.
Watmore played up front in a 3-1 defeat to Middlesbrough U23's, moving to the right wing at the beginning of the second half.
He played with trademark tenacity, showing the occasional burst of pace that will make him such a valuable asset for Jack Ross.
Ross watched Watmore's return alongside first team staff James Fowler, John Potter and Craig Samson.
The forward looked set to seal his comeback with a first half penalty, but was denied by a fine save from Brad James.
The penalty had been won thanks to a moment of superb individual skill from Sam Smart, who jinked in from the right flank, beating one defender before drawing a foul from another.
Smart is on trial from Basingstoke Town, who play in the Evo-Stik Southern Premier Division South.
The youngster had a trial with Sheffield Wednesday this summer after a spectacular season last time out.
Jake Hackett quickly made amends for Watmore's miss with a fine free-kick, striking the ball into the top corner from the inside right-channel.
Hackett was one of a number of youngsters to impress in a strong first half performance from the Black Cats, with Benjamin Kimpioka lively and Bali Mumba superb.
Mumba did play his team-mates into trouble on one occasion as the half came to a close but otherwise it was an eye-catching performance, the 17-year-old playing with typical poise and delighting the crowd with one turn away from danger.
Middlesbrough fought back strongly in the second half and missed a penalty of their own when Ben Liddle hit the post.
Watmore and Smart were taken off and the scores were level soon after when Connor Malley scored a fee header from a corner.
The visitors were well on top and took the lead when Daniel Ward fired home a loose ball from inside the penalty area.
The second half collapse was completed when Walker fired in a third.
Watmore could be in contention to make his first team return in the Checkatrade Trophy next week, when Sunderland welcome Notts County in the first knockout round on Tuesday.
Alternatively, he could play another U23 game when Wolves visit next Monday.
"I'm delighted for him," Ross said before the game.
"He's now done seven weeks of training with me, which is a long time but we've been really patient but it's been good for him because he now believes he's back.
"This will be another huge step for him.
"It's a proper game and once he gets that out of the way he's pretty much there, which is brilliant for him.
"More than anything, for him personally. To get through what he's been through you have to be a strong character and he certainly is that."
Watmore was replaced by young striker Andrew Nelson, who stepped up his own recovery from injury.
Sunderland XI: Johnstone; Hunter, Young, Taylor, Bainbridge; Smart (Diamond, 57), Hackett, Mumba, Neil (Connelly, 75); Watmore (Nelson, 57), Kimpioka
Subs: Storey, Cameron
Middlesbrough XI: James, Spence, Robinson, Liddle, Stubbs, Wood-Gordon, Malley, Ward, McGill (Spence, 60), Walker, Brahimi
Subs: Hood, Balde, Hackney, Hemming