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Noah Rubin earns his first victory against a Top 10 opponent in the ATP Rankings, defeating second seed John Isner on Thursday.

Rubin Earns First Top 10 Win, Stuns Isner

De Minaur, Rublev also into the third round

American Noah Rubin arrived in Washington, D.C. at his career-best ATP Ranking of No. 152. But his level at the Citi Open has proven to be much higher than that.

Rubin shocked second seed John Isner 6-4, 7-6(6) early Thursday evening to move into the third round, which he will play later Thursday against #NextGenATP Russian Andrey Rublev, who finished off his second-round win against American Tommy Paul 7-6(5), 6-4.

"I was just grinding every point out, making sure that I capitalised on the points that I didn't do at the French Open," said Rubin, who lost to Isner in straight sets earlier this year at Roland Garros. "I was really keen on those big moments, and just had fun with it."

It is the first time Rubin has beaten an opponent inside the Top 10 of the ATP Rankings, and also the first time he has won multiple matches at a tour-level event. He arrived at the ATP World Tour 500-level tournament with two tour-level victories this season.

Isner started his campaign in the nation's capital playing the tennis of his life. The American won his first ATP World Tour Masters 1000 title earlier this season at the Miami Open presented by Itau, reached the semi-finals at Wimbledon and he had maintained his momentum by lifting the trophy last week at the BB&T Atlanta Open.

Rubin’s next opponent, Rublev, was not the only #NextGenATP player to reach the third round on the fourth day of play. Aussie Alex de Minaur surprised recent Dell Technologies Hall of Fame Open  champion Steve Johnson 6-4, 7-5. He will face reigning Next Gen ATP Finals champion Hyeon Chung later Thursday evening.

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