Kent seam bowler Simon Cook and top-order batsman Justin Kemp have both failed fitness tests ahead of tonight's vital Twenty20 Cup qualifier in Hove.
Cook was hit on the left shoulder on Wednesday night by a rasping drive from Surrey's Abdur Razzaq and the joint has bruised and stiffened considerably since.
His place goes to Robbie Joseph, who will be making his Twenty20 Cup debut.
Kemp, who missed the six-run defeat to the Browncaps in Canterbury with back spasms, is also unfit and is again replaced by Matt Walker.
Holders Kent need to win tonight's 10th and final Southern Division tie to stand any chance of qualifying for the knock-out stages.
Middlesex can not be caught and will finish as group winners, while Essex and Hampshire, the two other teams one point above Kent, play each other.
So unless the Eagles and the Hawks tie or are rained off, the best Kent can hope for is a qualifying spot as the best third-placed finishers in all three zonal groups with 12 points.
Looking ahead to the tie Kent coach Simon Willis said: "We're still in with a chance of qualifying and there's a good chance for the lads to go out and put in a decent performance at Hove.
"Twenty20 is all about confidence and if you're feeling good about your game things tend to go your way, but if there's a little bit of doubt there you tend to take a chance and it seems to go against you.
"Maybe we've just been lacking in that department at times but I'm hoping the guys will play with freedom against Sussex and show what they're capable of."
He added: "I feel we still have a performance in us. We haven't performed with the bat as we know we can, the boys know that, but they still have a chance to turn things around.
"The big thing about Twenty20, as we proved to ourselves last year, it's all about qualifying for the knock-out stages. Do that, then you have three games ahead of you to become cup winners.
"We've got a few niggles which we've had throughout the tournament to be fair."
The gates at Hove open at 3.30pm and though some tickets will be for sale at the turnsiles, Sussex officials suggest Spitfires fans arrive early to avoid disappointment.