Yahoo Sports reports: Naomi Osaka's Wimbledon preparations received a setback when she retired at the start of the second set in Saturday's Bad Homburg final because of a foot injury. The fourth-seeded Japanese player, in her first grass-court final, was trailing 6-1, 1-0 to Karolina Muchova of the Czech Republic when she pulled out. Osaka had taken a medical timeout in the first set.