Russia's Daniil Medvedev said it was "great for the self-esteem" to win a 10th career title on the eve of replacing Rafael Nadal as world number two.
The top seed cruised to victory in Marseille on Sunday, beating 93rd-ranked Frenchman Pierre-Hugues Herbert 6-4, 6-7 (4/7), 6-4 in the final.
The 25-year-old will climb above Nadal to number two in the world in the ATP rankings on Monday, behind Novak Djokovic.
Medvedev will be the first player outside the 'Big Four' of Djokovic, Nadal, Roger Federer and Andy Murray to reach number two since Australia's Lleyton Hewitt in July 2005.
"I am really happy. I knew that I would become No. 2 no matter what on Monday," said Medvedev, the runner-up to Djokovic at the Australian Open final last month.
"It is always better when you step up the rankings when you do something great.
"I know that winning here didn't give me the points to become No. 2, but it is great for the self-esteem that just before becoming No. 2 on Monday, I win a tournament.”
On Sunday, Medvedev fired 13 aces past Herbert who had stunned second seed and two-time champion Stefanos Tsitsipas in the quarter-finals.
Six of Medvedev's titles have come on indoor hard courts -- the biggest of which was at last year's ATP Finals in London.
"I am really happy about the number 10. It gets me to two digits, something which I dreamt of when I was a kid," added Medvedev.
"I think it is already a great number, but I am going to try to work more and get some more.
"I really like to play on hard courts. I feel like that is where my game suits me the best. I feel like I know the solutions I have to find during the match and that is what I did today."