Kai Rooney's first appearance for Manchester United's Under 21s didn't go to plan, when the Reds went up against Nottingham Forest in Loughborough on Friday

Kai Rooney's debut for Manchester United's Under-21s ended in heartbreak.

The 16-year-old son of United legend Wayne was as a second-half substitute during Friday's Premier League 2 fixture against Nottingham Forest at Loughborough University Stadium. He came on in the 78th minute with the Reds drawing level at 2-2 and searching for that all-important winning goal.

Rooney would have been hoping to have made the difference with a goal on his first appearance for the Under-21s. Instead, however, United lost the game 3-2 with Shakur Samuels netting a late winner for Forest.

It marked United's first Premier League 2 defeat of the season. They had won their opening three matches, scoring 12 and conceding three goals, beating Ipswich Town, Leicester City and Brentford.

Ahead of the trip to Forest, Rooney showed his excitement about the chance to feature for the Under-21s on Instagram. He posted a picture of his kit hanging on the wall in the changing room with the caption: "U21s vs Forest."

Rooney's debut for the Under-21s came less than a week after he made his maiden appearance for the club's Under-19s in the UEFA Youth League against Atletico Madrid. But the Reds were beaten 3-0 in the Spanish capital.

The youngster has been promoted through the United youth system after featuring for the club's Under-16s last season. He was handed a scholarship - a full-time, two-year apprenticeship agreement - with the Reds in July.

It's believed the contract would switch to a three-year professional deal worth around £50,000-per-year with an annual signing-on fee. He is among the most talented youngsters in the United academy right now.

Wayne, who made his debut in the Premier League at the age of 16 as he emerged as a talent at Everton in 2002, has previously spoken about his son's qualities.

He told former United team-mate Gary Neville on The Overlap: "[He has] my physique, but he'll be taller than me and he's a goalscorer, he's in the box, he sniffs chances out and that's his game, so he's doing OK."

Neville asked him: "Obviously you can't remember yourself, but is he at that sort of level where you think he's got a chance, or is it too early?" Rooney replied: "I think it's too early, you never know.

"I think he's showing potential and good signs."