The 26-year-old arrived at Everton's Finch Farm training complex on Thursday morning with the club having applied for a work permit and awaiting international clearance for a one-year loan deal.

It is not expected that the medical reports will be concluded until Friday, so the chances of the 21-year-old being able to face Portsmouth on Saturday are slim.

Castillo has been with Red Star Belgrade for the past two years and has 33 caps.

But boss David Moyes' first signing this week, Danish defender Lars Christian Jacobsen, is set for a place in the squad.

The club received his international clearance earlier on Thursday but he is unlikely to start in the Premier match at Goodison Park.

He has been a free agent since leaving Nurnberg at the end of last season and has been training back in Copenhagen and lacks match fitness.

Everton are also chasing Inter Milan winger Victor Obinna on a loan move.

Obinna is a Nigeria international colleague of Everton's Victor Anichebe and only joined Inter earlier this week.

But the Italians have decided to send him out on loan, and Everton are aiming to bring the player to the Premier League.

Everton dropped out of the race for Shaun Wright-Phillips because they could not match his wages, with the player having now joined his former club Manchester City.

Everton are still searching the market for new signings, and may well try again for Sporting Lisbon skipper Joao Moutinho, but it is unlikely they will be able to prise Stephane Mbia away from Rennes.