Simon Grayson was impressed by Dutch goalkeeper Robin Ruitter, but says he won't make a rash decision on his future.
Ruitter made a string of fine saves on his debut as Sunderland beat Bradford 3-2.
The former FC Utrecht keeper did himself 'no harm', in Grayson's words.
He said: "I think as a manager I’d rather judge him in training than in a game because he’s made loads of saves, which means he’s been overworked. But in terms of his play, he was composed with his feet, very calm and made good saves when he had to.
"That’s what you want, he’s got good experience. We’ll have a look at him, whether we sign him or keep him for a few days and play him on Wednesday and take a look, that’s a decision we’ll make. He’s done himself no harm, but you can’t be rash on a player you haven’t seen too much."
Grayson also said he is hopeful of adding new players to his squad quickly. The Sunderland boss has been linked with moves for Bournemouth pair Marc Wilson and Lewis Grabban, as well as Aston Villa's Ross McCormack.
He said: "There’s plenty of movement behind the scenes and we want to get one or two deals done very quickly as it is two weeks until the season starts. Believe me, if you had my phone for a day you’d know what it is all about.
"We’re speaking to players, agents, and clubs, there’s positive signs but it is about getting down to the nitty-gritty and getting deals over the line."
Aiden McGeady is yet to make his Sunderland debut, again missing out on Saturday.
Grayson said the winger had picked up an injury but is confident that he will make a quick return.
He said: "McGeady picked up a slight injury but we expect him to train on Monday with a view to playing on Wednesday."