WIMBLEDON, England — For Cori Gauff, 15, and Felix Auger-Aliassime, 18, Monday at Wimbledon was a day for teenage dreams coming true after their first victories at a Grand Slam tournament.

But established stars only slightly older seemed to treat first-round losses like midlife crises.

Naomi Osaka, 21, lost in the first round for only the second time in 14 Grand Slam main draw appearances.

After becoming the first player in more than a decade to win her first two Grand Slam titles consecutively,