They have completely dominated the Championship match with a massive total of 561-8 declared, their highest of the season.
That left Sussex needing to beat their previous best of 411 just to avoid the follow-on.
And skipper Mike Watkinson was determined not to waste such a strong position with Lancashire going for a third consecutive win which could take them into the top half of the table - especially after seeing a similar position in the opening game of the season against Durham slip away because of the weather. ``If we had won the Durham game, we could already be in the top four,'' said Watkinson, who finally emerged from his injury nightmare by thumping 75 off 89 balls in the Lancashire innings, his first half century since the Durham game, including two consecutive hooked sixes off West Indian paceman Vasbert Drakes.
Lancashire's bowlers then continued the punishment, reducing Sussex to 137-5.
Peter Martin maintained his superb recent form by firing out openers Neil Lenham and Rajesh Rao, both lbw, in a pacy spell of 8-5-4-2.
Then Ian Austin, who had earlier added an unbeaten 77 to the 97 he scored against Sussex in the NatWest defeat at Hove last week, sent back Bill Athey and Keith Greenfield with consecutive balls.
Former Kent veteran Neil Taylor showed some fight with an 85-ball half century and moved to 82 by lofting Gary Yates over long on for a four and a six in the same over. But Yates continued to give the ball plenty of flight and gained his reward when Taylor mistimed a drive and was caught by Darren Shadford at cover.