First Division leaders Middlesex are well placed to claim their third successive win after another bowler-dominated day at Hove.
Twelve wickets fell on a second day that ended with 21 overs unused after a sea fret rolled in.
Middlesex closed on 126 for six, having extended their overall lead to 203 after dismissing Sussex for 192 earlier in the day.
No player has yet passed 50 in the match (their have been 112 extras) and that statistic looks unlikely to change with batsmen on both sides struggling to combat a pitch of erratic bounce that is unlikely to get any easier.
Sussex were indebted to Ben Brown’s counter-attacking 46 for keeping their first-innings deficit to manageable proportions and although Middlesex slumped to 68 for four and then 102 for six, Ollie Rayner defied his former team-mates with an unbeaten 19 before the mists descended.
Sussex were hampered by the absence of their leading wicket-taker Ajmal Shahzad, who suffered an arm injury on the first day. In his absence Ollie Robinson took three wickets to take his tally on his home debut to seven which just about kept Sussex in contention.
Batting again with a precious lead of 77, Middlesex lost Nick Gubbins in Robinson’s first over when he edged an away-swinger before Steve Magoffin reaped an instant reward for a change of ends when he plucked out Sam Robson’s off stump.
Middlesex lost two wickets with the score on 68. Substitute fielder Simon Harmer ran out Nick Compton (33) with an under-arm throw from the covers and James Franklin completed a pair off the next ball when Magoffin had him taken at second slip.
Robinson’s lifter accounted for Neil Dexter and Mike Yardy claimed his third slip catch of the innings shortly after tea when Adam Voges drove at another Robinson delivery that spat up off a length.
Rayner and John Simpson survived for six overs before the players went off.
We just need to knock over their last four wickets tomorrow and see where that takes us. We have fought hard and we still feel we have a chance to win the gameMark Davis
Earlier, Sussex’s first innings had been something of a procession once skipper Ed Joyce shovelled a leg-side ball from James Harris to long leg in the second over of the day.
Luke Wright briefly flourished with five boundaries in his 26 but it needed Brown to give the total some respectability. He attacked vigorously after lunch, hitting eight boundaries in a stand of 31 for the ninth wicket with Shahzad, who offered solid support despite clearly inconvenienced by his injury.
Brown gave Rayner his second wicket with a tame catch down the leg side while the pick of the Middlesex seamers was Toby Roland-Jones, who found the right length and was unfortunate to only finish with two wickets.
Sussex Head Coach Mark Davis said: “It’s been another intriguing day and I guess a good one for the neutrals with 13 wickets and some good batting.
“There are runs to be scored. Ben Brown and Luke Wright showed that if you are positive you can score quickly but we are probably behind the eight-ball a bit.
“Ajmal Shahzad’s absence is a blow for us. He’s got a grade one tear of his pectoral muscle in his right arm and will probably be out for 5-6 days. With three other seamers injured it’s a problem but I thought Steve Magoffin and Ollie Robinson ran in hard for us. If you can bowl a consistent line and length there is something in the wicket for you.
“We just need to knock over their last four wickets tomorrow and see where that takes us. We have fought hard and we still feel we have a chance to win the game.”
Ollie Rayner - Middlesex off-spinner - said: “When I played here the wickets were low, slow dustbowls designed for Mushtaq Ahmed so as a spinner myself I definitely prefer pitches like this which have bounce.
“We’re over 200 ahead so we are in a strong position but we know Sussex will keep fighting hard, they are not a side that rolls over for anyone.
“But our seamers have bowled really well. Toby Roland-Jones is only just coming back after a shoulder injury but he gave us good control and was unlucky to only get two wickets. Hopefully they can do a good job for us again in Sussex’s second innings and if I can contribute then great.”