Qualifier Oscar Otte knocked out No.7 seed Jan-Lennard Struff 6-4, 6-3 in an all-German matchup during the first round of the bett1HULKS Indoors in Cologne.
Steve Johnson also won a first-round upset, beating fifth-seeded Filip Krajinovic of Serbia 3-6, 6-4, 6-4.
Sixth-seed Hubert Hurkacz of Poland, Austrian Dennis Novak, Radu Albot of Moldova and German wild-card entrant Mischa Zverev all progressed.
In Sardinia wild-card Lorenzo Musetti beat No.8 seed Pablo Cuevas of Uruguay 7-6 (4), 7-5 in day one of the event at Santa Margherita di Pula, Sardinia.
Musetti, 18, will meet Italian qualifier Andrea Pellegrino in the next round after his opponent Stefano Travaglia retired while trailing 5-6, 7-6 (7), 3-0.
NO.7 seed, American Tommy Paul, and Czech Jiri Vesely both won their openers.
Aryna Sabalenka began her quest for a third straight title at the US Open as…
Carlos Alcaraz ended a four-and-a-half month injury exile with a resounding 6-4, 6-4, 6-4 defeat…
Williams has lost her last 15 matches as a wild card, with her last victory dating…
Novak Djokovic hit the wall as the 24-time Grand Slam winner vomited at the back…
Third seed Jessica Pegula got up and running on Sunday's opening day at the US…
Former finalist Casper Ruud made a last-minute pull out on Sunday as the US Open began,…