Middlesbrough boss Gareth Southgate believes summer signing Tuncay will get even better.
After a slow start to life at The Riverside by the Turkish striker he has now netted twice in his last two outings, including the winner at Derby.
Southgate believes international disappointments hindered his early progress in England, although he thinks the striker can produce even more despite a fine run of form.
"We still have a way to go away with him," revealed Southgate.
"He had a few difficult games with Turkey earlier this season - a bad result against Greece, long flights travelling back from the weekend, which left him slightly below par for us.
"A couple of times I did not include him in the starting line-up because of the week's events with Turkey, so it has taken him a while to get on the scoresheet.
"We put him on the bench and his response has been excellent. The last three weeks in particular, you can see what goals have done for his confidence.
"He's different in style to any other player I've come across. He's quite a free spirit. There is plenty in there - and plenty still to come out."