Harrington had a total of 27 birdies and an eagle in Paris this week
Padraig Harrington hit top form ahead of the Ryder Cup with a 64 in the final round of the Vivendi Cup in Paris.
The 39-year-old Irishman, a captain's pick for the big event at Celtic Manor, only made the cut by one shot and was last after five holes of round three.
But he had seven birdies and an eagle three at the long 13th on Sunday to finish joint eighth on 13 under par.
Yorkshire's John Parry carded a 70 to reach 17 under and claim his maiden European Tour title by two shots.
Harrington's round equalled his best of the year and earned him a fifth top-10 finish in 10 European events this season.
The Dubliner has dropped from third to 22nd in the world rankings since his last win at the 2008 USPGA Championship.
He chose to add Paris to his schedule after failing to qualify for the lucrative Tour Championship in the United States.
After struggling to a 74 on the Retz course on day two, he returned to the Marly, sole venue for the final two rounds, and posted 15 birdies and an eagle in his final 36 holes.
He narrowly missed a putt for a two after finding the green into the breeze at the treacherous 210-yard 17th, but a fine approach to the last gave him an eight-foot birdie chance that he calmly rolled in to post the lowest score of the final round.
Harrington's round was perfectly timed, but he did not want to enter discussions about whether it was the correct decision by captain Colin Montgomerie to choose him ahead of Paul Casey and Justin Rose for Celtic Manor next week.
Parry hold aloft the unusual Vivendi Cup trophy after his impressive win
"At the end of the day it's impossible to prove any point like that," he said. "Everybody's going to have their opinion and most people will be pretty committed to their opinion.
"It's not something I can control, so best to stay away from it, but I'm obviously happy. The week before a big event is all about seeing where your game is at and what needs working on.
"I struggled putting earlier in the week and it was sharp today, so I don't have as much to work on.
"I am excited to get there and ready to go."
For Parry, meanwhile, securing his tour card for next season was almost as satisfying as holding his nerve to win the title following the disappointment of leading at half-way in last week's Austrian Open and falling away to finish 20th.
"I didn't feel comfortable in the lead in Austria, but I came here, practised hard and played really well - and I feel really comfortable in the lead this time.
"The win means to much to me because I was 116th in the money list and fighting to keep my playing card for next year. Now I know I have got one and can go ahead and plan the whole of 2011."