No. 2 seed Andy Murray, who is trying to become the first British man to win the Wimbledon singles title since Fred Perry triumphed in 1936, easily won his first-round match on Monday with a 6-4, 6-3, 6-2 victory over Benjamin Becker of Germany.
"It's obviously surprising but that's sport, and Rafa's not played on the grass this year either," Murray said in an interview with the BBC.
"It's obviously an upset, but if you're a little bit off, that can happen."
In a matchup of promising young American players, No. 17 Sloane Stephens of Plantation, Fla., defeated Jamie Hampton of Auburn, Ala., 6-3, 6-3. In another all-American matchup, Christina McHale of Englewood Cliffs, N.J., defeated Alexa Glatch of Newport Beach, 6-4, 6-4.
In general, though, it was a rough day for American women.
Petra Kvitova of the Czech Republic, the 2011 Wimbledon champion, defeated Coco Vandeweghe of Rancho Santa Fe, 6-1, 5-7, 6-4 after Vandeweghe fought off one match point. Varvara Lepchenko of Allentown, Pa., was eliminated by Eva Birnerova of the Czech Republic, 2-6, 6-4, 4-6, Melanie Oudin of Marietta, Ga., lost to Michelle Larcher de Brito of Portugal, 6-7 (7-9), 6-1, 4-6, and Vania King of Long Beach was eliminated, 6-4, 3-6, 1-6, by No. 29 Alize Cornet of France. Also, Lauren Davis of Gates Mills, Ohio, lost to 27th-seeded Lucie Safarova of the Czech Republic
Top-seeded Serena Williams is set to play her first match on Tuesday, against Mandy Minella of Luxembourg.