Sunderland defender Tom Flanagan admits Manchester City youngster Callum Doyle walked into a skeptical dressing room when arriving on-loan.

Flanagan and Doyle have formed a promising defensive partnership, with the experienced 29-year-old speaking honestly about the Blues youngster.

When Flanagan first heard about a young centre-back joining from City, he admitted that he had a few questions - and a few eyebrows were raised.

"I remember when we signed him there were big question marks in the dressing room, I don't think anyone is afraid to say that," Flanagan said.

“He's 17 and from Man City - can he head a ball? They don't really do that much at Man City."

But after seeing Doyle come in, work hard in pre-season training - there's no doubting that he quickly earned the respect of his teammates.

On match day, he put it all together in his first game in pre-season - and hasn't looked back since.

Flanagan said: "He's stood up to every single test and he's getting better and better.

"He will have a period out of the team [because he's young] and that's what happens but he's a standout performer, not just in our team but in the league."