"I do not beat around the bush, we told Athletic Bilbao that we are interested in the player and I'm optimistic about his contract. He will play for Juventus from July 1," the 57-year-old told Radio24.
Marotta went on to say the club is always monitoring the transfer market, but claimed that a move for Napoli star Edinson Cavani would be incredibly unlikely.
"We watch the market carefully, if there are possibilities of improving the group will try to catch them. [Cavani] is not only elusive for Juve, but for all the Italian teams," he added.
Juventus currently tops the table of Serie A with a five-point lead over second-placed Napoli.