India, Aug. 21 -- Aryna Sabalenka's dream of completing a three-peat at the year's final Grand Slam, the US Open, suffered another blow when she lost her fourth-round match against 20-year-old Czech Sara Bejlek at the Cincinnati Open. The World No. 1 crumbled under pressure against a lower-ranked opponent, squandering a 5-1 lead in the first-set tiebreak and then throwing away a 4-1 advantage in the second set before losing 7-6 (9-7), 6-4. With New York just days away, Sabalenka's aura has taken a serious hit and, more worryingly, the question of whether the Belarusian has mentally checked out is becoming harder to ignore.

The defeat also leaves Sabalenka's position at the top of the WTA rankings vulnerable, with Elena Rybakina able to t...