Sussex 69 for 1 trail Kent 575 (Northeast 190, Dickson 81, Denly 78, Stevens 63, Blake 61, Briggs 5-169) by 506 runs
Kent skipper Sam Northeast crossed 1000 first-class runs for the summer as Kent continued to dominate neighbours Sussex in Tunbridge Wells.
At the mid-point of their County Championship match at Tunbridge Wells, Sussex had reached 69 for 1 in reply to Kent's season's best total of 575 all out. The visitors' sole casualty was Harry Finch bowled when playing back in defence to a Mitch Claydon off-cutter that appeared to keep low.
Northeast had batted in a short sleeved sweater for well over six hours in the hottest conditions of the year to post the fourth century of a golden summer and the 15th of his career.
"I was thinking to myself at one point why on earth have I got this jumper on, but it's become a superstition," conceded Northeast. "We've a nice total on the board and a lot of runs to play with but it's going to be hard work for us tomorrow. That said, there are encouraging signs for the bowlers already. There's a little bit of slow turn for the spinners, it was reversing a bit at the end there and KG [Kagiso Rabada] was making it talk on a seriously slow deck, so we'll need to work hard for our wickets."
Having bolstered his career-best in recent weeks with scores of 189 (v Glos), 191 (v Derbys) and 166* (v Essex) 26-year-old Northeast looked nailed on for his first double hundred until he slightly mistimed an attempted straight drive and saw bowler Steve Magoffin pull off a return catch diving to his left.
He showed his frustration by turning around to flick off the bails with his bat, but his 244-ball stay with 13 fours and a six had secured his side a dominant position in this Division Two clash.
Resuming on their overnight score of 310 for 3 and with Northeast unbeaten on 75, Kent suffered only one casualty in the morning session.
Darren Stevens, the club's hugely popular beneficiary for 2016, reached a typically belligerent 63 before his ambition got the better of him. Having just slog swept one from Danny Briggs to the ropes, Stevens aimed to repeat the dose only to sky a catch to Will Beer at midwicket.
Northeast joined forces with Alex Blake to add 127 inside 30 overs either side of lunch with Blake reaching his 50 with a six over long-on against the legspin of Will Beer. It was the left-hander's second six to go with three fours. His fun ended for 61 with a missed sweep and an lbw appeal against Danny Briggs that made it 457 for 5.
Briggs struck again when James Tredwell also skied to square leg and, once Northeast departed, the Kent tail soon rolled over.
On his home debut emergency wicketkeeper Callum Jackson scored a creditable 38 before becoming the last of Briggs's hard-earned haul of 5 for 169.
Sussex head coach Mark Davis paid tribute to Briggs' and his side's tenacity with bat and ball. "It was a good effort to get through the final session today and only lose one wicket in the face of a good spell from Kagiso Rabada. It's obviously going to be hard work over the next two days as the pitch deteriorates, so we must go out there with a clear game plan and make sure we fight our corner.
"It was a very good toss for Kent to win and we tried to set some fields that made them think, but generally we stuck to our task and it was really exciting for 'Briggsy' to get his first five-for for the club."