Dominik kopefer

Alcaraz received a second-set retirement from Dominik Kopefer (ankle) in his opening match, but got the opportunity to stress test his game against the powerful 26-year-old Afrcian on Thursday night.

The youngest US Open top seed in tournament history, Alcaraz defended nine of 10 break points faced and recovered from being a break down midway through the third set.

The Spaniard, who is looking to become the first back-to-back champion at Flushing Meadows since Roger Federer won five straight titles from 2004-2008, improved to 55-6 (18-3 on hard) on the season. He is chasing his seventh title of the season and third career major.