Shakhtar Donestsk have confirmed Chelsea are interested in signing Brazilian ace Willian, but that he will not be sold for less than his buy-out clause.

Chelsea boss Andre Villas-Boas admitted over the weekend he was an admirer of Willian, but played down talk of a move for the player in this month's transfer window.

Shakhtar are believed to have rejected one offer in the region of £20million for Willian with the Ukrainians holding out for £29million for the playmaker.

Shakhtar are reluctant to lose Willian, but they concede the South American is keen on a move to Chelsea.

"We have no burning desire to sell the player, but in football some things are impossible to avoid," Shakhtar CEO Sergei Palkin is quoted as saying in the Daily Mail.

"If it weren't for our good relationship with Chelsea - and Willian does not hide his intention to test himself in one of the best clubs in the English Premier League - we would insist on the £29m release clause written into the player's contract.

"It is important to understand that we are talking about Chelsea's desire to buy Willian, but not Shakhtar's desire to sell him."