Sri Lanka legend Kumar Sangakkara played one of the finest knocks of his long career at The Oval as Surrey beat Nottinghamshire by four runs to reach their first Lord's final in four years.
The 37-year-old former Test star hit 166 out of Surrey's total of 300-5.
Notts slumped to 16-3 when teenager Sam Curran took two wickets in two balls.
Greg Smith made 124, sharing big stands with Samit Patel (51) and Dan Christian (54) but, in a thrilling finale, Notts fell just short on 296-7.
Surrey will now play Gloucestershire, conquerors of Yorkshire the previous day, in the One-Day Cup final on Saturday 19 September.
Sangakkara batted almost the whole of the Surrey innings, arriving at the crease in the third over when opener Steven Davies edged to slip, before holing out off the first ball of the the final over almost three hours later.
By then he had hit a six and 13 fours, but despite all his running between the wicket clearly taking its toll he was fresh enough to plunder 62 runs from the final 10 overs as the Surrey innings built to an exciting climax.
Notts were able to pick England's Stuart Broad for the first time in a one-day game since he played in their 87-run win over Glamorgan at Lord's in the 2013 YB40 final.
But, while he was not needed for one-day international duty against Australia this week, Notts opener Alex Hales and captain James Taylor both were, which weakened the visitors' batting.
When young Curran removed both Riki Wessels and Brendan Taylor in successive deliveries before Michael Lumb also went cheaply in the fifth over, it looked as if Notts had no chance.
But, on his List 'A' debut for Nottinghamshire, former Leicestershire batsman Smith helped turn the game around, sharing a 92-run stand with Patel before putting on a further 112 with Christian.
But a clever piece of captaincy by Gareth Batty got rid of the big-hitting Australian when he snared him in a three-man offside trap at short third man.
Even then, with Smith in such fine form, Notts were still favourites, but he was cruelly run out by Tom Curran backing up - and the target of 14 from the final over proved too much.