Oliver Glasner is making his first Nottingham Forest mistake after Jair Cunha latest

Oliver Glasner should not be letting Jair Cunha leave Nottingham Forest as talks are held over a move to Vasco da Gama.

Forest are in for a huge summer window as Glasner shakes up his squad following his arrival as their new boss.

They have already sold Elliot Anderson to Man City for a British record fee, while centre-back David Carmo has joined Olympiacos.

Glasner mainly deployed a back-three formation during his time in charge of Crystal Palace, and is expected to do the same in the East Midlands.

There are several options at his disposal, but young Brazilian centre-back Cunha looks unlikely to remain in his squad for next season.

He is closing in on a return to his home country with Vasco da Gama, but Glasner looks to be making a mistake considering his previous performances.

Jair Cunha deserves a chance to prove himself to Oliver Glasner

Cunha joined Forest from Botafogo a little over a year ago, and made 15 appearances across all competitions in his debut campaign at the club.

He was often left behind Murillo, Morato and Nikola Milenkovic in the pecking order under their four different managers, yet put in several strong showings when called upon.

The 20-year-old played 90 minutes in a back-three as Forest drew 2-2 at Man City in March, then started and impressed in their 1-0 Europa League win against Porto a month later.

Further strong performances in wins against Burnley, Sunderland and Chelsea followed, and he looked to be coming into his own under Vitor Pereira before the season ended.

It seems hugely short-sighted from Forest's board and Glasner to be in talks to let him leave, particularly as reports state that he could be set to sign a loan-to-buy deal with Vasco.

Not only that, but both Murillo and Milenkovic have been linked away from the club in recent times, so they could be left very short at the back if one of them also leaves after Cunha.

Ola Aina has revealed why Forest should keep Cunha

Sources have revealed to Football Insider that Glasner and Evangelos Marinakis have already disagreed on some aspects of the club's summer window, and it is unclear if the new manager is behind Cunha's impending exit.

Forest right-back Aina previously heaped praise on the 20-year-old ahead of their European clash against Aston Villa in May.

After being asked about Cunha, he said: "He’s been wicked, hasn’t he? I think he has been. Obviously, at the start of the season, he wasn’t playing as much, so maybe people didn’t see how good he is.

"But we see him every day in training. If he keeps his head down, like I think he will do, he’ll go a long way.”

It clearly makes little sense to let Cunha leave this summer, especially with a fellow professional singing his praises like Aina has.