Out-of-contract midfielder joins in pre-season training with the Rams.
Free agent John Eustace is training with Derby County.
Derby boss Nigel Clough is a long-time admirer of the veteran central midfielder, who is out of contract after leaving fellow Championship side Watford this summer.
The 33-year-old is a player who has been on Clough’s radar for some time after enjoying a loan spell at Pride Park during the final months of the 2008-09 season.
He made nine appearances in total and scored once, ironically against his parent club Watford at Vicarage Road on the final day of the season.
Eustace teamed up with the Rams last week for the start of pre-season training ahead of the 2013-14 season at Moor Farm Training Ground and is due to remain with Derby for the next few weeks.
Clough explained: “John is training with us and he’s going to spend a couple of weeks at Moor Farm.
“We’ll see what that brings and we could possibly do something with him.
“He can play as a holding midfielder or even at centre-half, which would be ideal in terms of what we’re looking for because there aren’t too many of his type around.
“We’ll sit down and have a chat with John either later this week or early next week and get his views on how he sees things developing.
“John is someone we’ve liked for quite a while and he’s got a lot of experience to offer, so we’re interested in seeing if we can explore things a bit further.
“He’s a good character, which we know from his loan spell with us a few years ago, and he’s already familiar with the set-up.
“We don’t have too many experienced players in the squad, there’s only Lee Grant and Ben Davies who are in their 30s, but there’s always room for two or three to look after the young lads.”
Eustace has made 381 professional career appearances for seven different clubs, after starting his career at Coventry City in 1996.
He has also enjoyed spells at Dundee United, Middlesbrough, Stoke City, Watford and Derby.