Kevin Keegan is to delay making a decision on Shay Given's fitness until the end of the week.
The Newcastle goalkeeper sustained a groin injury in the 4-1 defeat at Aston Villa last weekend.
It was initially thought to be a reoccurrence of an old problem but Given later stressed that he was confident of making a quick recovery.
However, he remains doubtful for Saturday's Premier League clash against Manchester United and Keegan admits he may have to turn to Steve Harper.
"Shay is saying all the right things and thinks he has a chance, but Friday will be the day when we decide that," Keegan told the club's official website.
"He still has a chance and we'll know more later in the week.
"If Shay's not fit, Harps is ready. We're in safe hands either way.
"As clubs go we have two of the best keepers in the Premier League if you take them as a pair."
Obafemi Martins could miss the match with United after returning from the Africa Cup of Nations with an ankle knock.
"Oba is looking doubtful for Saturday but I wouldn't rule him out just yet," said Keegan.