Crawley could be without first-choice centre-backs Claude Davis and Kyle McFadzean when they host Sheffield United.
Davis is a doubt after jarring his knee against Stevenage last weekend and McFadzean is struggling for fitness after an illness.
Shaun Cooper is still out with a groin injury so young duo Joe Walsh and Mark Connolly, who finished the 2-1 win over Boro, could start at the back.
Striker Billy Clarke missed that game with hamstring trouble and will be checked over.
Teenage forward Jonte Smith, back from a loan spell with Met Police, was on the bench for the first time last weekend and will hope to be involved again.
Midfielder Josh Simpson is set to make his 100th appearance for the club.
Sheffield United manager Danny Wilson hopes to include Kevin McDonald in his squad.
The Scottish midfielder missed last week's goalless draw with Tranmere due to an ankle problem, but has trained this week and could feature if he suffers no adverse reaction.
Striker Dave Kitson is another key player for the Blades who Wilson hopes to call on this weekend. The former Stoke forward had been sidelined for almost two months with a hamstring injury before stepping off the bench for the last 27 minutes against Tranmere and he could get a longer run out on Saturday.
Wilson has no other new injury or suspension problems as his side bid to go back to the top of the table, but goalkeeper Mark Howard (thigh) and defender Lescinel Jean-Francois (knee) remain sidelined despite returning to training.