Sydney FC youngster Terry Antonis is expected to miss the Sky Blues' first home game of the A-League season against Newcastle Jets on Saturday because of the concussion suffered against Wellington Phoenix.
The 18-year-old remains in New Zealand and won't return to Australia until Tuesday after hospital staff in Wellington wouldn't allow him to fly back with his teammates on Sunday.
Antonis was taken to hospital immediately after Sydney's season opening 2-0 loss to Wellington on Saturday night.
The talented midfielder received a head knock early in the match against the Phoenix but managed to play on until the 59th minute when he was replaced by Ali Abbas.
Sydney coach Ian Crook told AAP on Monday he expected Antonis to be unavailable for the clash with Newcastle at Allianz Stadium, in a match which is expected to attract a big crowd for the first home game of Alessandro Del Piero.
"I'd be surprised if he was involved this weekend. He's not even back in the country yet, they've kept him there in New Zealand," Crook said.
"He's flies back tomorrow (Tuesday). He obviously wasn't at all good after the game and he'll be assessed when he returns home."
Goalkeeper Mat Ryan, defender Pedj Bojic and midfielder Oliver Bozanic look to have played their last games for Central Coast Mariners as the A-League champion faces a raft of departures.