CLYDESDALE BANK 40 GROUP A, Hove:
Surrey 240 (38.3 ovs) tied with Sussex 240-8 (40 ovs)
Pietersen celebrates reaching his century against Sussex
England batsman Kevin Pietersen returned to form with 116 as Surrey tied their last CB 40 game with Sussex.
Pietersen smashed six sixes and eight fours in his 105-ball knock and shared 105 for the second wicket with Jason Roy as Surrey were all out for 240.
Murray Goodwin then hit 81 and Chris Nash 53 to keep Sussex in the hunt.
They were left needing four off the final ball to tie, and Ollie Rayner obliged by hitting Tim Linley down the ground to take Sussex to 240-8.
The tie meant the two sides ended their Group A campaign in the same positions as they had started the day, with Sussex finishing second and Surrey third to miss out on the semi-finals.
And it left England as the only winners as Pietersen reached three figures for the first time in 18 months and for the first time in domestic one-day cricket for seven years.
His presence in the Surrey team helped attract a 5,000-strong crowd to Hove, and they soon saw him in action as captain Rory Hamilton-Brown holed out to deep square leg off the fifth ball of the visitors' innings to bring Pietersen to the crease.
He played second fiddle to Roy in their second-wicket stand, the teenage batsman making 60 off 49 balls, including seven fours and a six, before being bowled by Monty Panesar.
Pietersen then struggled for partners as wickets fell regularly at the other end, one of which was his fault as he called Gary Wilson through for a risky single only to see him run out by Joe Gatting.
He reached his 50 off 55 balls and then took only another 46 to bring up his century, and hit four of his sixes off Raynor before finally being yorked by James Kirtley.
His return to form certainly came as no surprise to Paul Collingwood, who told BBC Radio 5 live before Pietersen's innings: "KP is a world class player.
"Everybody goes through dips in form and confidence is obviously low. I'm sure he is desperate to score runs for Surrey. That is important for the bigger picture going to the Ashes and the World Cup.
"It's a huge winter. Hopefully him regaining confidence and form will put us in a great position as a team as well.
"I'm very confident he will regain form. Nothing has changed in his technique, it's all mental. Once he gets that confidence back he will get that swagger back and start hitting the ball like he did in the Twenty20 World Cup."