Patrick Vieira believes his Manchester City teen star Jack Byrne is just as "nuts" as his former nemesis Roy Keane.

After consulting with first-team manager Manuel Pellegrini, City reserve team coach Vieira opted to send 19-year-old Dubliner Byrne on loan to Dutch club SC Cambuur for the season.

The Irish U21 midfielder had been granted a new three-year contract by Pellegrini ahead of last month’s move and the Frenchman reckons the temporary stint abroad will be integral in the youngster developing into the player City chiefs reckon he can become for club and country.

Vieira even likened the diminutive midfielder to compatriot Roy Keane for his temperament — a trait he feels can help rather than hinder the prospect’s career graph.

“The only way to compare Jack and Roy is that they are both nuts,” remarked the former Arsenal skipper after City’s development squad lost 3-2 against St Patrick’s Athletic in Wednesday night’s friendly at Richmond Park.

“That can help, especially when you’re Irish. You have to have it, as we’re in a world of competition and the desire and personality will make a difference.

“Sometimes people get it wrong between having a personality and being stupid and cocky. But Jack Byrne has personality. I don’t know any top quality player who doesn’t have that. It’s part of his character and I’ve never had any issues with him. I love him more than anything else.

“On the ball, he is technically very good. He understands the game quicker than anyone else. I’ve worked with Jack for the last few years and he really improved in the last year. It was fantastic, especially in the last three or four months, as he was one of my best players.

“He got to the level where I didn’t expect, to be honest. He showed me that I was wrong and that’s why I’m really pleased with him, as he worked really hard. Physically he knew it was one of his weaknesses and that’s why I’m glad he went to Holland. I hope he plays games and does well and we’ll see what level we get to.

“It was time for him to play ‘man’ football. Holland was the best option and we decided together that it was a really good step for him.

“If you want to play direct, Jack will be useless but if you want to keep the ball on the floor, and you need someone really creative, Jack will be the player who can do that.”

Ireland assistant manager Keane has suggested he would call Vieira, who he jokingly referred to as “my pal”, to ascertain whether Byrne is capable of graduating to the senior international squad. His former midfield foe is ready to give a ringing endorsement.

“I think they are right to do it,” he said. “Jack has the potential but the potential is not enough to play in the first team so they have to work hard and show how much they want to make it. It won’t be easy but when you have the talent and the desire, it’s just a question of time.”

“That’s not just for seven or eight months, but to work hard for the next 10 years if he really wants to make it. The hard work dictates which level you will play at. But the potential is there.” Another Irish prospect at the Etihad, Ian Lawlor, has not enjoyed as much good fortune as Byrne in the past year. The gifted goalkeeper was the rising Irish star of 2014, earning a senior Ireland call-up after graduating to City’s Champions League squad, but injuries dogged him last season.

Vieira said: “Ian is coming back from injury and before thinking about going out on loan he has to get fit, train and play. Of course, he is one of the players we are trying to find a loan for but we have to find the right place for him to play and improve.”