ASTANA, Kazakhstan -- Carlos Alcaraz's first match as the No. 1-ranked player ended with a straight-sets loss to David Goffin at the Astana Open on Tuesday.
Alcaraz, 19, lost 7-5, 6-3 in his first tour match since winning the US Open and capturing the No. 1 ranking.
"David was playing really, really well. To come back to competition is never easy," Alcaraz said. "It's really tough for me, for my confidence."
Alcaraz came from 5-2 down to level the first set at 5-5, only to be broken again by his Belgian opponent.
"When you play against the World No. 1 on a big stage, big crowd, the fire inside gives you so much power to play your best tennis because you don't have any choice," Goffin said. "You have to fight and give your best and that was the case today."
Second-seeded Daniil Medvedev and No. 3-seeded Stefanos Tsitsipas both avoided similar upsets. Medvedev beat Albert Ramos-Vinolas of Spain 6-3, 6-1 and Tsitsipas ousted Kazakhstan's Mikhail Kukushkin 6-3. 6-4.