Former Sheffield United defender Rob Kozluk has returned to Bramall Lane on trial.
Kozluk, 32, released by South Yorkshire neighbours Barnsley at the end of the season, is among five new trialists with United.
The trialists include former Swansea defender Tom Williams and three from overseas, who will join up with the Blades squad for pre-season training by Monday.
Manager Kevin Blackwell said: "Kozzy and Tom Williams have come here to join in with pre-season, neither of them have got clubs so we can have a good look."
Blackwell added: "The two lads from France and Belgium are here and the lad from Spain will arrive on Monday.
"They are all good technically and have potential but we want to see if they can handle the physical aspect of the game in this country."