The 25-year-old arrived at the Riverside Stadium during the summer transfer window with a big reputation, and has already shown signs of the talent in which Boro invested so much faith.

However, reports from Turkey have suggested he is unhappy in England and feels he has not been given a chance to prove himself by Boro.

But Southgate, who looked on as Tuncay apologised to his team-mates in the dressing room after missing three good chances at West Ham on Saturday, has issued a passionate response as he prepares to name him in his squad for the derby clash with Sunderland this weekend.

He said: "It's nonsense, so I am not prepared to be distracted from our preparations for Saturday's game.

"I actually saw these supposed quotes from Tuncay a couple of weeks ago and asked him about them. There is no truth to them.

"He is committed to the challenge. His reaction to the game last Saturday certainly didn't suggest to me someone that wasn't 100% committed to the club and what we are trying to do.

"He has been a substitute for some of our early games, but there is every chance he will be playing against Sunderland on Saturday.

"The truth is that we have been delighted with him and I am sure he will be a big success over here.

"He's a smashing character and a great professional."

Tuncay headed for Teesside, lured by the pulling power of the Barclays Premier League, after turning down a new deal at Fenerbahce, where he had established himself as a national star.

The experienced international, who has a Champions League hat-trick against Manchester United to his name, was signed in the wake of Mark Viduka's defection to Newcastle, which came as a huge blow to Boro.

However, he was never recruited as a direct replacement, but rather as an attacking midfielder who could operate in and around a striker.

He has played his early football for the club as a right-sided midfielder, although was used in a central role at Upton Park after replacing the injured Jeremie Aliadiere with just 30 minutes gone.

His record as a goalscorer - he managed 77 in a little more than 200 appearances for Fenerbahce and has 13 international goals from his 43 caps - illustrates his potency, and he was unfortunate not to open his Boro account in the 3-0 defeat at West Ham.

Only the woodwork denied him his first goal for the club when he lobbed keeper Robert Green and saw the ball bounce on top of the crossbar and run to safety.

Tuncay's long-term role seems likely to be in behind target man Mido and the pacy Aliadiere, although in the short term, he could play as an out-and-out frontman.

Boro have confirmed that the Frenchman pulled a hamstring last weekend and is set to sit out the next month.

That leaves Mido, Tuncay and South Korea international Dong-Gook Lee to fight it out for places in attack against Sunderland with the first two likely to get the nod after combining well against the Hammers.