England one-day captain Eoin Morgan scored 83 not out off 29 balls to help Middlesex to a record T20 Blast run-chase and seal a quarter-final spot.
Somerset set Middlesex a target of 227 to win at Taunton, with Tom Abell finishing 101 not out for the hosts.
Coming in during the ninth over with his side 111-3, Morgan’s superb knock helped Middlesex to victory with three overs to spare.
Middlesex’s successful chase was also the fourth-highest in T20 history.
Meanwhile, Essex beat Kent to secure the final place in the last eight as the group stage reached its conclusion on Friday.
Five teams had gone into the final round of South Group fixtures with hopes of reaching the quarter-finals.
- Lancashire Lightning v Essex Eagles
- Notts Outlaws v Middlesex
- Sussex Sharks v Worcestershire Rapids
- Gloucestershire v Derbyshire Falcons
More to follow.