Young opener Max Holden sent records tumbling as Middlesex secured a home quarter-final with a 33-run win over Kent in the Royal London One-Day Cup.
Holden batted until the penultimate over as he perfectly paced Middlesex to their highest List A total of 380 for five while also surpassing the county's record individual score in the format.
The 21-year-old reached 166 from 139 balls – to overtake the previous record of 163 held by former England captain Andrew Strauss – and send Middlesex into the knockout stages of a domestic 50-over tournament for the first time since 2009.
New Zealand international Ross Taylor added 94 but Middlesex were still made to sweat for the win as Kent's own young opener Zak Crawley led the pursuit with 120.
Crawley's dismissal, to the tournament's leading wicket-taker Nathan Sowter, slowed Kent's momentum before they were bowled out for 347.
Middlesex will host Lancashire in a Lord's quarter-final on Friday while Somerset will travel to Worcestershire after they emerged from a three-way battle for the remaining play-off place in the South Group.
Somerset had lost their past three matches to put their qualification hopes in doubt but held their nerve to chase down Surrey's 289 for nine with five wickets in hand.
James Hildreth top scored with 93 while Jamie and Craig Overton had earlier combined for seven wickets.
Gloucestershire and Sussex, who had both started the day with hopes of progressing, were therefore left outside the play-off places.
James Bracey hit an unbeaten 113 to guide Gloucestershire to a four-wicket win against Essex, who had posted 293 on the back of Varun Chopra's 156.
Glamorgan produced a record chase at Hove as half-centuries from Billy Root, Marnus Labuschagne and Daniel Douthwaite saw them to a two-wicket win. A Laurie Evans century and 97 from Luke Wright had helped Sussex to 347 for seven.