Middlesbrough boss Gareth Southgate hopes to have Tuncay Sanli available for their next game against Chelsea.
"It's a possibility (to return against Chelsea). He's progressing very well. I think any team would miss a player of his ability, enthusiasm and character," he told the club's official website.
"The energy he gives to the stadium, never mind the team, is huge. He's been missed within the group but he's working incredibly hard and he's training with us now.
"He had a couple of weeks in Turkey because their national team were hoping he could get fit for these couple of weeks so we knew that would help us. Now he's working extremely hard here, training both morning and afternoon to get back.
"He doesn't enjoy sitting in the physio's room and working in the gym. He wants to be playing football and he will be as soon as he's available."