Alex Michelsen, a 20-year-old unseeded American, produced the biggest win of his young career with a 7-5, 6-3, 2-6, 6-4 first-round upset of 2023 Australian Open runner-up Stefanos Tsitsipas on Monday.

Alex Michelsen produced the biggest win so far of his fledgling career to upset 2023 runner-up Stefanos Tsitsipas in the first round of the Australian Open and the first person he credited was his mom.

Stefanos Tsitsipas twice smashed his racket onto his bag as he exited the Australian Open in the first round against young American Alex Michelsen. Tsitsipas, who is enduring a miserable run of Grand Slam form,

Young American Alex Michelsen caused the first big upset of the Australian Open by knocking out former finalist Stefanos Tsitsipas in the opening round. Tsitsipas was beaten by Novak Djokovic in the final two years ago and is also a three-time semi-finalist, but he has struggled since reaching the quarter-finals of the French Open last spring.

American Alex Michelsen claimed the biggest win of his career when he stunned Stefanos Tsitsipas 7-5 6-3 2-6 6-4 in the first round of the Australian Open on Monday as the Greek 11th seed became the first major casualty at Melbourne Park.

Stefanos Tsitsipas (No. 11) faced a surprising first-round exit against Alex Michelsen (No. 41). The American had previously defeated Tsitsipas in their only prior meeting at the Tokyo Open.

MELBOURNE: American Alex Michelsen claimed the biggest win of his career when he stunned Stefanos Tsitsipas 7-5

Rising American star Alex Michelsen defeats Stefanos Tsitsipas, showcasing his rapid ascent in professional tennis and highlighting the growing wave of young U.S. talent.