Quebecer Leylah Fernandez threw in the towel during her match against Tatjana Maria when the score was 6-7 (7) and 4-0 in favor of the German on Tuesday in the first round of the San Diego tournament.
Fernandez, seeded eighth and 32e racket in the world, won only four of the 13 rallies she started with balls in hand in the second set.
However, she started the match by winning four games in a row. She notably managed a break in the third game, which required 24 rallies.
Fernandez also erased a set point during the tiebreaker before winning the set following a serve from his opponent.
It was a second victory for Maria (47e) in as many duels between the two women. The European won 6-3 and 6-2 last year in Cleveland.
Marino beaten in Austin
Canadian Rebecca Marino was defeated 6-2, 6-4 by Sachia Vickery in her first round match at the ATX Open in Austin, Texas.
The British Columbian dominated 8-1 in aces, but the American had the advantage 5-2 in breaks.
Marino is 147e at the WTA, Vickery 134e.
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