Santos remain confident they will persuade Diego to put pen-to-paper to return to Brazil.
Diego spent seven years with Santos before embarking on his European career in 2004.
His current deal with Wolfsburg is due to expire at the end of the season and the German outfit appear keen to keep him until then at least - despite interest from elsewhere.
As well as Santos, Premier League side Southampton have also been credited with an interest.
Speaking about both Diego and Ivica Olic - himself linked with a Premier League move - sporting director Klaus Allofs said: "We know the two and know exactly what we have in them.
"They are a very important part of this group, but we must take the time to see how the entire team develops."
Santos vice-president Odílio Rodrigues added: "He is still waiting for a position from his club in Germany, as they have the preference.
"He respects his contract and will see what happens in Germany first, then we will talk again."