Gunning has missed the last two matches and was sent for a scan on a shin injury earlier this week.
"He has got a slight nick on his shin-bone so it is another two weeks for him,” manager James Rowe said.
Kellermann went off at half-time against Maidenhead United in midweek.
Rowe explained: “He won’t make tomorrow. He is out. He has twisted his hip. It is nothing major but it will be 10-14 days.”
Fellow midfielder Manny Oyeleke, who has been managing an ongoing calf problem for a while, will be assessed.
Rowe said: "We need to monitor Manny and see if he can play his third game in seven days. We need to be careful on that one so we don’t lose him for the long-term. It is a big decision on whether we start him tomorrow or not.”
Joe Rowley, who has been out with an ankle injury since October, is back available for selection again.
On Saturday’s opponents, Rowe added: "Their form has picked right up in the last nine games. They were in a relegation dogfight but they seem to have come out of that a little bit but they still need to pick up points obviously. You are not safe until you get to that 50-point mark in the National League.
"They are going to go all out to try and get a positive result and a positive result for them would be one point so we have got to be aware of that and make sure we start right.”