Cardiff will allow long-serving Kevin McNaughton to leave this summer along with Danny Gabbidon and Nicky Maynard.
Highly-rated Atletico Madrid midfielder Saul Niguez has signed a new five-year contract.
Juventus have put a 100million euros price tag on star midfielder Arturo Vidal.
The 26-year-old, who was a target of Real Madrid this summer, has enjoyed a fine start to the campaign scoring three times in Juve's opening three Serie A games.
"If (Real Madrid's Gareth) Bale is worth 100million euros, Vidal is also worth that figure," Juve general director Giuseppe Marotta said to Mediaset Premium.
"Vidal is a great player and this summer Real Madrid showed an interest in him but we turned it down. Selling him is simply out of the question."
The Chile international greatly contributed to Juve winning back-to-back Serie A titles.
Juve are now moving fast to offer the former Bayer Leverkussen player, whose current contract expires in 2016, an improved deal as a sign of their intentions to keep him.
Marotta has also underlined his club's position regarding midfielder Paul Pogba, who was linked with a return to the Premier League this summer.
The 20-year-old French international has established himself as a regular in Antonio Conte's team.
Pogba moved to Juve after three seasons at Manchester United and scored five goals in 27 league appearances for the Italian champions last term.
"Just as with Vidal, our view on Pogba is the same," Marotta said. "He has unexpectedly stolen the limelight and I want to congratulate him and Conte, who has managed to bring out the best in him.
"Pogba is an important element to our team and all the offers that we received for him (this summer) we turned them down.
"With regards to his contract, if his talent becomes a reality at the highest level, as we hope it will be the case, then we will reward him with an increase in wages."