Kevin Pietersen enjoyed a solid knock of 38 on his Surrey debut but was ultimately left disappointed as Worcestershire secured a 90-run win at The Oval.
The dropped England batsman shared a second-wicket stand of 79 with skipper Rory Hamilton-Brown as the hosts attempted to chase down Worcestershire's mammoth target of 377.
However, Pietersen could not go on a make a big score and the Royals innings, which included centuries from Vikram Solanki and Gareth Andrew, proved more than enough for victory.
Pietersen, who has recently been in the headlines after his hastily-retracted Twitter response to his England axe, survived an early lbw appeal before getting into his stride.
The 30-year-old dispatched three well-timed sweeps to the boundary off the bowling of left-arm spinner Shaaiq Choudhry and reached the ropes six times in total.
But his innings came to an end after he chipped a return catch to the same bowler as the 8,000-strong crowd sensed their faint hopes of reaching the Clydesdale Bank 40 semi-finals slipping away.
Despite Pietersen's presence, it was Hamilton-Brown who was provided the fireworks for Surrey, smashing four sixes in his 80 from just 41 balls.
After a middle order failure, Chris Schofield (37), Gareth Batty (29) and Chris Tremlett (38) tried in vain to keep up with the sky-high asking rate but the hosts were eventually dismissed for 286. Choudhry finished as the pick of the bowlers with 4-54.
Worcestershire had earlier put themselves in a commanding position from the start, with Solanki and Moeen Ali (41) opening with 61 in seven overs before the latter was dismissed by Jade Dernbach (3-64).
But the runs kept flowing and the hosts could do nothing to stop Worcestershire compiling a massive total when Solanki joined forces with Andrew in the middle.
The pair added 185 for the fourth wicket before Solanki dragged a Dernbach yorker onto his stumps for 129 from 89 balls.
Andrew was next to depart for an even more rapid 104 from 60 and Daryl Mitchell (35no) added some more quick runs in the final overs to leave Surrey with the third biggest run-chase in the history of the competition.