Bradford City manager Peter Jackson hopes to install a second senior goalkeeper at the club in the next week.
Former City keeper Rhys Evans and ex-Scotland Under-21 international Iain Turner have joined Jon Brain and Billy Lumley on trial at the club's Woodhouse Grove training ground.
Jackson, who has only one goalkeeper, Jon McLaughlin, in his first-team squad, said: "Jonny is still struggling with a virus. I think we may have to run some tests to get to the bottom of it, so it gives us the opportunity to have a look at a few goalkeepers.
"We will have seen a fair few by the end of this week, so we'll be looking to make a decision on this particular position in the next week or so."
Evans, 29, made 45 appearances for Bradford during the 2008/9 season, while Turner, 27, released by Everton, has had loans spells with Sheffield Wednesday, Nottingham Forest and Coventry in recent seasons.