Angolan defender Rui Marques will make his first pre-season appearance at Grimsby on Tuesday night, but midfielder Neil Kilkenny and defenders Jason Crowe and Richard Naylor remain sidelined.
Speaking to Leeds' official website, Grayson revealed Crowe and Kilkenny were making good progress and should be in contention for Saturday's game against Blackburn at Elland Road. Naylor, though, is still recovering from back surgery.
"Killa had to rest for a few days - that's why he missed out on Ireland - and Jason took a knock last week," he said.
"It's a precaution more than anything, but as I've said before, we're not in the business of taking risks or bringing players on too quickly."