Pretty much from the get-go at the U.S. Open on Monday, Madison Keys could tell she wasn't hitting the ball well or feeling very much at all like the self-confident player who claimed her first Grand Slam title at the Australian Open in January.

After 89 unforced errors, including 14 double-faults, the sixth-seeded American was gone from Flushing Meadows with a loss to 82nd-ranked Renata Zarazua.

Sometimes tennis can be absolutely brutal. Just ask Madison Keys, who walked into Arthur Ashe Stadium on Monday expecting to make a statement as the defending Australian Open champion.