Karl-Heinz Rummenigge is the latest to offer an update on Bayern Munich's pursuit of Javi Martinez, admitting a deal with Athletic Bilbao is 'complicated'.
He remains optimistic regarding Bayern's chances of snaring the Spain international, but a saga which has dragged on for much of the summer remains some way from being completed.
Martinez has expressed a desire to move on and Bayern have a five-year contract awaiting him at the Allianz Arena.
The fee involved in any agreement is proving to be something of a sticking point, though, with Bayern reluctant to match a €40million (£31.5m) buy-out clause.
They are, however, still working hard on a transfer, with Rummenigge hopeful the 23-year-old will soon be a Bundesliga performer.
"It's a very complicated clause, so the whole subject would cause certain legal and tax problems," he said.
"We're working on it and I hope we can announce a deal by the end of August. But it's not entirely easy.
"Due to the fact he's prepared to forego a great deal of money in return for the five-year contract we intend him to sign here, he's indirectly contributing to the transfer fee.
"It definitely means the total investment would be significantly reduced."
Bayern president Uli Hoeness has also expressed his concerns about the move and he fears it might not happen.
He told channel n-tv: "It looks at the moment as if the transfer will not work out."