in these tournaments which boosted his ranking to a career-high of No. 145 on 23 August 2021 after winning the San Marino Open and the Verona Challenger, making him the second youngest male player in the top 150. Rune entered the 2021 US Open Qualifying as the 24th seed. There, he won all three of his qualifying matches to qualify for the 2021 US Open for his grand slam debut. He played world No. 1 Novak Djokovic in the first round, where he lost the first set and won the second set in a tiebreak, but started to cramp late in the third set and eventually lost the match. Rune made his second ATP quarterfinal at the Moselle Open, after qualifying for the main draw. He double-bageled lucky loser Bernabé Zapata Miralles in the first round, and then upset fifth seed Lorenzo Sonego in the second round in three sets to make the quarterfinals. He lost in the quarterfinals to second seed Pablo Carreño Busta in three sets. On 4 November 2021, Rune qualified for the 2021 Next Generation ATP Finals. He finished the year ranked No. 103 in the ATP rankings. 2022: Three ATP Tour titles, first Grand Slam quarterfinal & Masters title, top 10 Rune made his debut in the top 100 of the ATP singles rankings on 17 January 2022 at world No. 99, making him the second youngest male player after Carlos Alcaraz to be ranked in the top 100. At the 2022 Open 13, he reached his first career ATP semifinal in the doubles tournament with partner Hugo Gaston, defeating top seeds Nicolas Mahut and Pierre-Hugues Herbert and Polish pair Szymon Walków and Jan Zieliński before losing to eventual champions Andrey Rublev and Denys Molchanov. In April, Rune received a wild card to the Bavarian International Tennis Championships, where he defeated world No. 3 Alexander Zverev in the second round for his first top 10 win in his career in straight sets to advance to his third ATP quarterfinal. He then overcame Emil Ruusuvuori and Oscar Otte to reach his first career ATP singles final. There, his opponent, Botic van de Zandschulp, was forced to retire with chest pain with the scoreline at 3–4, leading the 70th-ranked Rune to become the tournament's third youngest champion in the Open Era after Guillermo Perez-Roldan in 1987. The title propelled Rune into the top 50 on 2 May