Ecuador midfielder Segundo Castillo is on Merseyside undergoing a medical ahead of his move to Everton.
The 26-year-old arrived at Everton's Finch Farm training complex 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 on Thursday but he is unlikely to start in the Barclays 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.