Casper Ruud became the first player from Norway to reach the top 10 of the ATP rankings.
The 22-year-old hit No. 10 when the new rankings were released Monday. He also is the youngest occupant of the top 10 list.
"I am very excited and happy of course to reach this milestone," Ruud told ATPTour.com. "It's something I've looked up to and worked hard for for many years. To achieve it is a very nice feeling."
Earlier this year, he became the first man since Andy Murray in October 2011 to win titles in three consecutive weeks, doing so in Bastad, Gstaad and Kitzbuhel from July 12-31.
He also won the title in Geneva in May.
At the U.S. Open, which wrapped up Sunday, he lost to Botic van de Zandschulp of the Netherlands in the second round.
Despite his straight-sets loss in the championship round in New York, Novak Djokovic of Serbia remained No. 1 in the rankings. The winner, Russian Daniil Medvedev, stayed at No. 2.
They are followed in the rankings by Stefanos Tsitsipas of Greece, Alexander Zverev of Germany, Russian Andrey Rublev, Spain's Rafael Nadal, Italian Matteo Berrettini, Austrian Dominic Thiem and Roger Federer of Switzerland.
Nadal, Thiem and Federer have missed much of the summer season because of injuries.
--Field Level Media