|LV= County Championship Division One, Taunton|
|Somerset 289 & 107-4 beat Sussex 214 & 178 by six wickets|
|Somerset 21 pts, Sussex 4 pts|
Alfonso Thomas became the first player since 2000 to take four wickets in four balls in the County Championship as Somerset beat Sussex by six wickets.
The 37-year-old seamer removed Sussex trio James Anyon, Rory Hamilton-Brown and Ed Joyce for a hat-trick.
He then bowled Matt Machan with the first delivery of his next over and finished with figures of 5-40.
Sussex crumbled from 33-0 to 33-5 in 10 balls and were out for 178, leaving Somerset to score 107-4 to win.
The victory, sealed with a day to spare, put the home side top of Division One, although Yorkshire could overhaul them with victory over Nottinghamshire on Wednesday.
The last player to take four wickets in successive balls during a Championship match was Gary Butcher, for Surrey against Derbyshire and Thomas is only the 18th to do so.
Having trailed by 75 after the first innings, Sussex began facing an uphill struggle to avoid what would be only their second Championship defeat of the summer.
Starting the day at 26-0, they were quickly 33-3 as Thomas bowled Anyon (18), trapped Hamilton-Brown lbw and had Joyce caught behind within three balls.
In Joyce, the visitors lost the second-highest scorer in the Championship this year. His 667 runs have included four centuries, the most recent of which came earlier in the game.
Despite the further heroics from Thomas, Sussex eventually established a partnership through Ben Brown and Luke Wright (both 35).
But Thomas completed his five-for by having Wright caught, with Peter Trego (3-27) seeing off Brown and then Luke Wells, to leave the visitors 110-8.
The tail provided brief resistance through Steffan Piolet (30) and Will Beer (29), but both were removed by spinner George Dockrell.
Somerset made hard work of the 104 target though, finding themselves 42-3, before Nick Compton made an unbeaten 38 and a Craig Kieswetter (15) six saw them over the line.
BBC Radio Bristol's Stephen Lamb:
"Alfonso Thomas admitted it was one of the best days of his career, at Somerset or anywhere else but after celebrating his hat-trick ecstatically with his team-mates, he was not sure how to react after taking four in four.
"It was a day to remember forever at the famous old ground as five wickets in 10 balls went down for no runs, followed by a three-day win which took Somerset to the top of Division One in the Championship.
"It is all too common knowledge that they have never won the title, but why shouldn't they dare to dream?"
BBC Sussex's Adrian Harms:
"This was a disappointing defeat for Sussex, who never recovered from the four-in-four from Alfonso Thomas.
"After a great start to the season, a mixture of bad weather and two defeats by Somerset, means Sussex are without a win in six Championship matches.
"Injuries to Michael Yardy, Luke Wells and Jon Lewis, as well as Test call-ups for Chris Jordan and Matt Prior, mean the squad is stretched to the limit, and coach Mark Davis said they are actively looking at a loan signing to bolster the batting options.
"With difficult games against Yorkshire at Arundel next week, followed by a long trip to Durham, this is a tough period for Sussex."