7-6 (7/4) victory caps a breakthrough season for the 23-year-old and keeps alive his slim hopes of qualifying for the ATP World Tour Finals in London next month.
It was third time lucky for the 20-year-old Greek Stefanos Tsitsipas in Stockholm, defeating a qualifier Ernests Gulbis 6-4 6-4 in an hour and 21 minutes for his maiden ATP title, becoming the first player from his country to lift an ATP trophy!
Edmund had reached his first ATP final in April, losing to Pablo Andujar in Marrakesh, shortly after replacing the injury-hit Andy Murray as British number one.
Tsitsipas had lost his previous two finals, both this year to world No.1 Rafael Nadal. I was very focused, determined to win the tournament...
"He played a really good match".
He couldn't deal with the pressure and Tsitsipas broke him at love after four unforced errors from Gulbis, securing his first ATP title in one of the most memorable moments of his young career so far. "I wish that it's not the last one".More news: Cancelling Saudi Arabia arms deal would cost $1B: PM
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Tsitsipas booked a spot in his third career final-and third of the season-by making routine 6-3, 6-2 work of Fabio Fognini.
One break of serve proved enough for Monfils to take the opening set and the flamboyant Frenchman recovered from a break down to take the second to a tie-break, which top seed Edmund dominated.
It's the first win by a Russian in nine years at the Kremlin Cup.
Khachanov overcame Mannarino in just 55 minutes to become the first Russian victor of the men's singles at the Kremlin Cup since Mikhail Youzhny in 2009. Nicholas Kalogeropolous was the first Greek to make a tour-level final, doing so in Des Moines 35 years ago.
"When I was a kid and came to this arena to watch our top players, to ask them for autographs I always dreamt of winning this tournament".