Manchester United's attempt to sign Ander Herrera could be looking possible after the Athletic Bilbao president spoke out on a potential deal today.
Although United were not mentioned, a wide variety of Spanish sources, including AS and Marca, have backed up the assertion that they were indeed the club who made the bid.
The Bilbao president stated that the bid was rejected and the club were unwilling to "negotiate", although this appears to be a reference to agreeing a price below the release clause - later on, he also stated that "if [United pay the buyout clause] and the player wants to leave, we will discuss."
This is significant, because there have been suggestions that Spanish release clauses contain a level of complexity that mean it's not as simple as paying the release fee. However, many of the pieces doing the rounds in explaining this are now outdated, with the rules since changed. Barcelona didn't bother making Bayern Munich's attempt to sign Thiago too difficult, despite the resentment involved in the deal. And Bayern were also able to get Javi Martinez, whom Bilbao really didn't want to let go, without paying above the release clause.
What this suggests is that either the situation is misunderstood or that a change in the rules or recent legal rulings have ensured that the buyout clause is, more or less, the buyout clause. Bilbao's statement that they would "discuss" a move if the release clause was met appears to confirm this - it is significant that it's not a flat out denial.
Another United bid is probably likely quite soon on this, but the move does seem very realistic.