Kent ended day three at Canterbury on 254-4 in their second innings after being forced to follow on by Division Two rivals Glamorgan.
Former skipper Rob Key made 85 and Brendan Nash an even 50 but the loss of both batsmen with the score on 192 was a major blow to Kent, who will resume in the morning with a slender 11-run lead.
Veteran spinner Dean Cosker picked up two second-innings wickets for Glamorgan after it had been the Welsh county's seamers who had done the damage first time around.
Having laboured to 73-4 by the close of day two, Kent were only able to add a further 62 before they were bowled out for 135 in 46.5 overs.
Jim Allenby nipped one back to snare Darren Stevens leg before for 10 as he shouldered arms, then also dismissed Ben Harmison (12) thanks to a catch from wicketkeeper and captain Mark Wallace.
Geraint Jones, the acting Kent captain, drove over a full ball from Michael Hogan to lose his off stump before on-loan debutant Mitchell Claydon (three) drove to mid-on to gift Graham Wagg a second wicket.
Calum Haggett (nine) made a late, and fatal, decision to leave a shooting off-cutter from Michael Reed that took out off stump, leaving the home team 110-9.
Their last-wicket pairing of Charlie Shreck and Adam Riley enjoyed themselves in adding 25 - the second best stand of the innings, before the latter was dismissed by Cosker's fifth ball of the match.
It left Shreck unbeaten on 15 not out - only four short of equalling his career best - and also allowed Wallace to ask Kent to have another go with the bat.