Britain's Emma Raducanu is through to the last 16 of the Miami Open after opponent McCartney Kessler retired injured at the start of the second set.
Raducanu had been utterly dominant and needed just 30 minutes to take the first set 6-1.
An early break in the second set saw the 22-year-old race into a 3-0 lead, before American Kessler, 25, was forced to retire because of a back issue.
"I could tell something was up and it is hard to stay focused when your opponent is struggling," Raducanu told Sky Sports. "I wish her a speedy recovery because she has been playing so well.