Essex and Somerset booked their places in the Friends Provident Twenty20 semi-finals on Tuesday.
Mark Pettini and Matt Walker produced a stunning second-wicket partnership of 147 as Essex beat Lancashire by eight wickets.
Lancashire had earlier posted 183-6 but Pettini hit 81 and Walker was unbeaten on 74 to help Essex secure victory with five balls remaining.
In the other quarter-final clash, Somerset raced to a seven-wicket win over Northants at Taunton to seal their spot at finals day.
Northants stumbled to 112-6 after a disastrous start which saw them lose their first two wickets to run-outs within the first two overs.
Craig Kieswetter (33) and Peter Trego (30) gave Somerset a good start in reply and James Hildreth’s unbeaten 25 secured a comfortable victory with 18 balls to spare.
Somerset will now take on Nottinghamshire at the Rose Bowl on August 14th while Essex will face hosts Hampshire.