Switzerland's Michel Kratochvil is already out of the $800,000 Indianapolis tennis tournament. Kratochvil was defeated in the first round by Taylor Dent, 6-7, 6-2, 4-6.
Kratochvil gave away the match after Dent broke his serve for the only time at the beginning of the third set. The 20-year-old American needed only one match ball to close out the game.
Kratochvil was given treatment for back pain during the penultimate game.
Monday's match was the first encounter between the 22-year-old Bernese player and Dent, the son of a former Australian professional and Davis Cup competitor. Dent is 60 positions below Kratochvil in the ATP rankings.
Kratochvil's compatriot, women's world number one Martina Hingis, has announced her participation on Tuesday in the $15.8 million US Open, which begins on August 27. Hingis, who is suffering from a foot injury, declined to take part in the WTA tournament in Toronto.
The United States' Lindsay Davenport, France's Mary Pierce and the Russian Anna Kournikova, who are all suffering from injuries, have also skipped the Canadian women's tournament.
swissinfo with agencies