Michael Yardy produced a devastating counter-attack to put Sussex in control on an action-packed first day of the LV= County Championship match with Somerset at Taunton.
Somerset were dismissed for 244 after opting to bat, with Steve Magoffin claiming 4-65, and the visitors found themselves eight for two in reply on a green pitch, offering pace and bounce.
But Yardy took advantage of the fast outfield and some generous Somerset bowling to smash an unbeaten 94 off 79 balls, with 17 fours, adding 166 with Matt Machan, on 58 not out, as Sussex closed on 174 for two.
It was a bad day for Somerset captain Marcus Trescothick, who followed his decision to take guard first by being dismissed for a third duck in successive games, caught behind off James Anyon having failed to register in the Friends Life t20 victories over Gloucestershire and Northamptonshire.
The scoreboard then read four for two when Nick Compton edged a catch to Chris Jordan in the slips to give Magoffin his first wicket. The rangy Australian seamer proceeded to wreak havoc upon Somerset once more, having achieved match figures of 12-31 in the corresponding game at Horsham in May.
Anyon and Jordan found lift and movement as only James Hildreth and Craig Kieswetter, half-centurions with 66 and 55 respectively, offered much resistance among Somerset's gifted batting line-up.
Kieswetter ran himself out with an ill-judged single to mid-on and too many of his colleagues were guilty of poor shot selection against an accurate and penetrating Sussex attack.
It seemed the pitch would continue to aid the quick bowlers when Jamie Overton and Steve Kirby sent back openers Luke Wells and Chris Nash at the start of the visitors' reply.
But once they were removed from the attack, Trescothick found it impossible to set a field to his other seamers, who erred in line and length as Yardy and Machan batted with increasing confidence.
Yardy blitzed to his half-century off 40 balls, with 10 fours, while Machan matched his boundary count in getting to fifty off 56 deliveries. From 16 for one, they hammered 113 runs off the next 12 overs.
By the close the electrifying stand had transformed the day and game.