Sussex will head into the final day requiring 332 more runs with nine wickets remaining if they are to claim victory over Glamorgan in the County Championship.
Glamorgan captain Kiran Carlson changed the tempo of their second innings with his half century at faster than a run-a-ball, before leaving it to Sam Northeast to finish the job with 104 and set things up nicely for the final day’s play.
The victory target is a tall order in 113 overs on a wicket that remains hard to score on, as Sussex finished on 27-1, losing opener Tom Haines caught slip off Australian leg spinner Mitch Swepson.
Australian Nathan McAndrew was the pick of the Sussex bowlers getting his second four wicket haul of the match, while off spinner Jack Carlson bowled 28 overs for a return of 1-92 as the rest of the wickets were shared.
Glamorgan opener Zain ul-Hassan provided the slow and steady part to set the platform for captain Carlson, who injected some pace into the batting by getting 59 off 50 balls.
Ul-Hassan added 23 runs through the entire morning session as he progressed to 47 at the lunch interval, but even though it was slow it was also important with the Sussex bowlers finding a bit of bounce in the Sophia Gardens wicket.
He lost opening partner Andrew Salter early, while number three Thomas Bevan departed for 15, Ari Karvelas and McAndrew getting the wickets.
Northeast is usually fluent when getting his runs, but he too was watchful while progressing steadily through to the lunch interval.
Ul-Hassan departed first ball after the interval to a shot of unusually aggressive intent against Sussex off spinner Carson, and at that point the game changed with Carlson walking to the wicket.
He immediately unveiled an array of shots, happy to go over the top and also employ the reverse sweep, clearly intent on ensuring Sussex would bat before the day was out.
A swipe across the line to medium-pacer Tom Haines saw him depart LBW, while a series of Glamorgan batters came and went while trying to get Northeast up to his hundred.
Having gone through to that landmark with a series of big hits, Northeast was the last man out for 104, run out trying to keep the strike with the declaration imminent.
Sussex’s bowlers rotated their efforts and retained reasonable control, with Australian McAndrew the pick of the attack. They opted not to use the new ball and bowled more than 100 overs with the old ball.
Tom Clark and Tom Haines then walked out for the remaining 17 overs of the day, but Haines was dismissed LBW and Clark was joined by nightwatchman Ari Karvelas who batted out the rest of the evening to leave Sussex on 27-1 overnight.