Kent 155 (Bell-Drummond 55, van der Gugten 3-27, Harris 3-35) and 106 for 1 (Compton 38*) trail Glamorgan 327 (Kellaway 90, Ingram 87, Agar 4-58, Parkinson 4-103) by 66 runs
Ben Kellaway and Colin Ingram combined to give Glamorgan the ascendancy on day two before Kent frustrated the bowlers in the beginning of their second innings.
Kellaway, who struck a mammoth 181 not out maiden century in the reverse fixture, gave fears of déjà vu with 90, together with Ingram's 87 to combine for a 174-run partnership resuming from overnight.
Glamorgan finished on 327, damage limited by Matt Parkinson taking 4 for 103 to grind his way through the Glamorgan lower order after Wes Agar claimed four wickets to handle the top order on day one.
Ben Compton led in the visitors' controlled reply of 106 for 1. The opener closed in on 1,000 runs for the season - having needed a further 33 to pass the milestone in a race to be the first to do so this season.
Ingram and Kellaway continued to rebuild from their 47-run partnership on the first day as Glamorgan resumed on 125 for 4 after rolling Kent for 155 inside two sessions.
The engine room of Glamorgan's leading run-scoring pair tormented the rotating Kent bowlers with the aging Kookaburra ball. If the partnership was able to build overnight after a period of bowlers dominating, with the day starting 42 overs in Glamorgan's innings, the lack of movement created an opportunity to set up an unassailable lead.
A life early in the day came when a top-edged slog sweep landed in no-man's-land from Kellaway. It was the only such moment until lunch. The fifties came, as did the century partnership with hardly any notice.
The wicketless session looked inevitable until Ingram was disappointed to be given out caught at slip, questioning a bump ball at 12.59pm to give Kent something to be able to enjoy their lunch at 250 for 5.
As if unsettled by the loss of Glamorgan's newly appointed white-ball assistant coach, uncertain shots began to creep into Kellaway's game before he was drawn into a flighted ball to drive directly to cover off Parkinson, who set about tormenting the lower-middle order.
Ned Leonard added a flurry with two straight sixes on Glamorgan's way past a second batting point. His 25 from No.10 lifted the hosts, who had lost four wickets for 24 prior to his 45-run stand with a stubborn Chris Cooke for the ninth wicket.
As they did in the first innings, Jadyn Denly and Compton looked unfazed against the new ball. Asitha Fernando and Timm van der Gugten were unable to find their line before the latter walked off mid-over through injury.
Kellaway added control as the only frontline spinner in the side - Mason Crane was sent to play in the seconds, where he took 11 wickets in the match, a decision Glamorgan could come to rue.
James Harris found some reverse swing after tea and enjoyed a threatening spell against the left-handers, and his economical spell eventually helped account for Denly, who top-edged a slog sweep in a bid to lift the shackles.
The newly formed pair had no concerns in closing down the deficit and leading momentum through to day three.
