Scott Styris scored the joint-third fastest century in Twenty20 history as Sussex comfortably beat Gloucestershire at Hove to move into FL t20 finals day.
Sussex, the 2009 winners, posted a total of 230-4, the highest score from any team in the 2012 competition.
Styris made 100 not out off 37 balls with excellent contributions from Matt Prior (60) and Murray Goodwin (55).
Highest scores in 2012 FL t20
Gloucestershire could only reach 191-8 in reply as Sussex won by 39 runs, despite Dan Housego scoring a rapid 47.
The visitors won the toss and elected to field and that looked a good decision as Sussex slumped to 3-2 with openers Chris Nash and Luke Wright dismissed.
However, Prior, who played for England in the first Test against South Africa earlier in the week, added 60 off 38 balls before he was run out by Ed Young.
Styris hit nine sixes in his century to make the second highest individual score of the 2012 tournament, seven runs short of Somerset's James Hildreth, who made 107 not out against Glamorgan on 22 June.
Gloucestershire's James Fuller conceded 38 runs from one over as he bowled two no balls, one of which went for four byes and the other was dispatched to the boundary by Styris, who also hit two other fours and three sixes in the same over.
Styris also claimed the early wicket of Gloucestershire's Benny Howell to leave the visitors on 16-1 in reply.
Captain Hamish Marshall made 42 and Housego scored 47 off 24 balls before being bowled by Will Beer.
Alex Gidman added 44 and Fuller hit 26 off 12 balls but it was not enough as Sussex qualified for finals day for the third time in the tournament's history.
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Gloucestershire captain Hamish Marshall tells BBC Gloucestershire:
"Scott played one of those innings that you hope you never come across when you're on the opposition.
"But I'm proud of the way the boys performed. We got 190 which was a pretty good score normally.
"It's been a good competition for us and we've made strides with a young side.
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