
The Chile international's future will be in the spotlight this summer after his season-long loan with Derby expires and he heads back to Southampton.
Brereton Diaz has one year remaining on his contract with the Saints where he has made just 10 league appearances after signing for £7m from Villarreal.
This week, the former Nottingham Forest attacker has been thrilled how the move to Derby has worked out having become a regular starter under Eustace since his move last summer.
Asked whether it would be an easy deal to do, Eustace is hopeful that Derby can get it over the line but is mindful that other clubs will also be in the hunt.
"I don't know, we'll have to wait and see," Eustace said when asked about the prospect of the deal happening.
"Obviously, he'll be on a lot of other clubs' radars, I'm sure, as well, going into the next season, but I think we've made him feel very at home, and we've given him a fantastic opportunity.
"We've been patient with Ben as well, obviously, he hadn't played any games during pre-season, and it took him a while to get up to speed.
"I know Ben's been struggling through injury as well and he was really struggling on Tuesday night.
"He's shown his level of commitment, just turning up and playing for us when he's going through pain.
"I think he wants to be part of the club and fingers crossed we can get that done."
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