Jonny Evans has linked up with the Northern Ireland squad, but remains a doubt to face Slovenia.
Northern Ireland manager Nigel Worthington is waiting for an update on Evans' fitness as he struggles to shake off a virus.
The promising Manchester United defender did not fly out with the rest of the squad to Slovenia on Wednesday, but he has now been given the green light to travel to Maribor.
The 20-year-old is set to miss training on Thursday and Worthington will give him until the last minute to prove his fitness.
"I'm very pleased Jonny has arrived," said Worthington.
"He did not meet with us on Tuesday because of the virus. Part of the reason was he needed to be away from the other players so the situation could not spread.
"He won't train today (Thursday) but we will build him up in the next few days and hopefully he will be ready for Saturday."
Birmingham goalkeeper Maik Taylor returned to training on Thursday after a bout of flu.