Teenager Mark O'Hara has signed a two-year extension with Kilmarnock.
Real Madrid goalkeeper Iker Casillas insists he would welcome the arrival of David de Gea at the Bernebeu.
Manager Tony Mowbray is confident of keeping midfielder Josh McEachran at the Riverside Stadium for the rest of the season.
The 19-year-old has made 23 appearances since joining on loan from Chelsea in the summer.
There had been suggestions that Chelsea may invoke their right to recall McEachran, who suffered a recurrence of an ankle injury against Blackburn on Boxing Day.
But Mowbray told local radio: "I've had conversations with some of the Chelsea hierarchy and they're 99.9% sure he won't be recalled in January.
"Unless they have a catastrophe with injuries, I think Josh will be staying with us until the end of the season."
McEachran has made 22 appearances for Chelsea and played five games during a loan spell at Swansea City last season.
Middlesbrough sit fourth in the Championship and are two points off an automatic promotion place.