Downing's Injury - Long Term Or Not?
The England winger was injured at the weekend when Aston Villa midfielder Stiliyan Petrov stood on his ankle.
Boro have refused to confirm or deny reports of the break, but confirmed he had already been to see a leading specialist in London.
Boro statement: "We will not be able to assess the full extent of Stewart's injury until his bruising and swelling go down.
"We are still waiting for further tests and investigations to find out the best way to manage the problem.
"Stewart has already seen a leading orthopaedic expert in London and is in the best possible hands."