Andreas Weimann believes Ron Vlaar has become an even better player and would be delighted if he stays at Aston Vila.
Middlesbrough have signed experienced Greek goalkeeper Dimitrios Konstantopoulos on a short-term contract until January.
Konstantopoulos made 117 appearances for neighbours Hartlepool from 2003 to 2007 before moving to Coventry, where he played 31 games during a four-year spell.
The 34-year-old started his career with Greek side Kalamata and also played for Boro's Europa League opponents Egaleo before moving to England.
The Greek international has also played on loan at Swansea and Cardiff and has just finished a two-year spell at AEK Athens, where he made 39 appearances.