|LV County Championship Division One, Hove|
|Close of play, day three: Sussex 548-4 dec, Yorkshire 273 & 29-2|
|Sussex 7pts, Yorkshire 2pts|
Yorkshire must bat out the final day at Hove to avoid defeat after being made to follow on by Sussex.
After resuming day three on 21-0, Yorkshire were soon in trouble as Wayne Parnell (3-60) and Amjad Khan (2-61) reduced them to 33-3.
And although Joe Root hit 70 and Steven Patterson (53) struck his maiden first-class half-century, they were dismissed for 273, a deficit of 275.
Yorkshire reached stumps on 29-2 second time around, still 246 behind.
It leaves Yorkshire facing an uphill battle to avoid a third successive County Championship defeat, while Sussex are in sight of a third straight win.
Yorkshire got off to the worst possible start when Joe Sayers edged the second ball of the day from Khan to Ed Joyce at slip.
Khan then bowled Anthony McGrath for his 300th first-class wicket, with Sussex debutant Parnell, James Anyon and Monty Panesar also all picking up wickets before lunch.
Root added 65 with Adil Rashid for the sixth wicket before the leg-spinner padded up to all-rounder Kirk Wernars to give him his first wicket in county cricket with his 17th ball.
Parnell eventually got through Root's defences with a leg-stump yorker, and Ryan Sidebottom swiftly followed.
But Patterson dug in and added 75 for the ninth wicket with Ajmal Shahzad, passing his previous best of 46, made in the 2006 Roses match at Old Trafford in the process.
Parnell again ended the stand by plucking out Patterson's off stump, and Shahzad holed out to deep square leg, enabling Sussex to enforce the follow-on.
They had early joy too as Sayers edged his second ball to second slip off Parnell, and Chris Nash trapped Root leg before to ensure Sussex ended the day well on top.