Azeem Rafiq claimed a crucial breakthrough to give Yorkshire some late encouragement as they pressed for victory against Sussex and a flat pitch at Arundel.
The Yorkshire off-spinner, making his first LV= County Championship appearance of the season while Adil Rashid is absent on paternity leave, dismissed opener Chris Nash shortly before lunch on the final day.
Resuming 133 runs behind on 21-0, Sussex negotiated the majority of the morning session with some ease and advanced to 102-1, trailing by just 52 runs at lunch.
But the impressive spell of Rafiq from the Castle End, claiming 8-1-24-1, gave enough encouragement for Yorkshire to continue pressing for an unlikely victory that would send them clear at the top of division one.
Rafiq was introduced in the 17th over of the morning and struck in his third over when Nash, who had progressed to 53, edged to Adam Lyth at slip, pushing forward defensively.
Nash had provided the bulk of the runs during a 66-run opening stand, falling for 53 while partner Luke Wells was playing a more attritional role and had reached just 11 after 32 overs at the crease.
Wells was also given a lifeline shortly before lunch on 19 when Rafiq found another edge, only for wicketkeeper Jonny Bairstow to miss the catch and punch the floor in frustration.