The midfielder has not featured for the Red Devils since he suffered an ankle injury against Barnsley on the opening day of the season.
"He trained on Sunday and is back kicking a ball so I'm sure he will be available for selection this weekend," Gregory told the Crawley News.
"He has been out for a long time. He got a hefty kick and sustained ligament damage in his ankle and it was a matter of looking after the swelling, looking after the pain and you get a lot of internal bleeding in this kind of situation.
"Even as recently as last Thursday he was still feeling uncomfortable, but he had an injection at the start of last week and I certainly think that has helped it to settle down."
Crawley are currently in 18th place in the League One table following three wins, five defeats and a draw from their opening nine matches of the season.