While Serena Williams has won the first three major tournaments this year, at times she has looked frustrated and vulnerable. She lost nine sets in her first 21 matches and was forced to play three tiebreakers. That pattern surfaced again in a second-round match Wednesday at the United States Open when Williams had to scrounge out a victory over Kiki Bertens, the 110th-ranked player in the world.
Williams withstood Bertens’s aggressive approach and her own nerves to win, 7-6 (5), 6-3. She needs five more wins to become the sixth player to win the Grand Slam in a calendar year.