Alex Michelsen of the United States upset third-seeded Lorenzo Musetti of Italy 3-6, 7-6 (4), 6-4 on Thursday in the third round of the National Bank Open.

Alex Michelsen defeats longtime friend and fellow American Learner Tien to advance to his first Masters 1000 in Toronto.

At 20, Michelsen is the youngest American man to reach the quarterfinals in Canada since Andy Roddick in 2003.

Alex Michelsen of the U.S. reacts after defeating Karen Khachanov of Russia in their third round match at the Australian Open tennis championship in Melbourne, Australia, Saturday, Jan. 18, 2025.

Alex Michelsen of the U.S. gestures during his third round match against Karen Khachanov of Russia at the Australian Open tennis championship in Melbourne, Australia, Saturday, Jan. 18, 2025.