The pair have been ruled out for the foreseeable future after they both underwent knee operations on Wednesday morning.
Kenyon has suffered a bucket handle tear to his medial meniscus of the left knee during training on Friday morning and will likely be out of action for up to two months.
Fleming’s scan however has revealed a more severe injury in that the 30-year-old has a chondral defect to the weight-bearing surface of his left knee.
He will likely be out for five months with a six week non-weight bearing period following surgery.
Bentley said: “It’s an absolute hammer blow to lose another two valuable members of the squad to injury.
“They are both big players for us and in the case of Fleming, we’re arguably losing our best performer this season so far.
“On top of James Sinclair’s injury it’s been a terrible few days for us injury-wise but it’s part and parcel of football.
“We have to accept it, remain positive and it now creates opportunities for others to step up and perform.”
Meanwhile, Jim Bentley says he is proud of his side’s efforts after two successive victories have helped lift the gloom over the Globe Arena.
Victories over Macclesfield and Grimsby have seen the Shrimps climb to 17th in the League Two table as they prepare to host Tranmere Rovers this weekend..
Bentley said: “Although there has been pressure on us I have said for a long time that the performances had warranted more. We had been in every game apart from the Crewe one but the lack of goals was an obvious issue.”
“We seem to have gone some way to resolving that and although we are delighted with the two wins we know we can do better.’’