Sunderland trialist Robbin Ruiter impressed in Saturday's 3-2 friendly win against Bradford, but no decision has yet been made about a contract offer, says manager Simon Grayson.
Goalkeeper Ruiter, 30, left FC Utrecht at the end of last season and has been training with the Wearsiders.
The Black Cats sold keeper Jordan Pickford to Everton for £25m, and Vito Mannone joined Reading for £2m.
"He's done himself no harm," Grayson told BBC Newcastle.
"But you can't make rash decisions on a player you've not seen too much in the flesh. As a manager I'd rather judge him in training rather than loads of saves in a game because that means he's being worked too much.
"In terms of his overall play, he was composed with his feet, very calm in possession and made a save when he had to. That's what you want from your keepers."