WASHINGTON — Australian Open champion Caroline Wozniacki pulled out of the Citi Open because of an injured right leg Tuesday, when the hard-court tournament also lost its defending champion, Ekaterina Makarova.
The No. 4-seeded Makarova lost her first-round match at the U.S. Open tuneup to Ana Bogdan 7-6 (2), 6-3.
No. 2 seed Sloane Stephens, the reigning U.S. Open champion, moved into the second round with a 7-5, 6-4 victory over Bethanie Mattek-Sands. Stephens converted all four break points she earned, saved seven of the nine she faced, and hit six aces. She’ll next face Andrea Petkovic, who won her opener on Monday.
In other results Tuesday, No. 3 Naomi Osaka beat Bernarda Pera 6-2, 7-6 (4), and No. 7 Donna Vekic defeated Caroline Dolehide 6-3, 6-4.
No. 1 seed Wozniacki’s withdrew hours before she was to face qualifier Anhelina Kalinina of Ukraine. Wozniacki was replaced in the field by Ysaline Bonaventure, who lost in qualifying.
After practicing on-site Monday, Wozniacki said her leg is “just something that has been nagging a little bit, but hopefully it’ll be fine.”
She won her first Grand Slam title in January at Melbourne to return to No. 1 in the rankings. She is currently No. 2.
Wozniacki hasn’t played a match since losing in the second round at Wimbledon on July 4.
She now has less than a month to get ready for the U.S. Open, which starts Aug. 27.
HALLE, Germany (AP) Alexander Zverev and Karen Khachanov bounced back from disappointments in Stuttgart last week to reach the second round of the Halle Open on Monday.
Second-seeded Zverev defeated Robin Haase 6-4, 7-5, while Khachanov celebrated his first match as a top-10 player with a 7-6 (5), 6-4 win over Serbia’s Miomir Kecmanovic.
Nine-time champion Roger Federer is the top seed at the grass-court tournament, a warm-up for Wimbledon. Federer is due to play Australia’s John Millman on Tuesday.
Both Zverev and Khachanov lost their opening matches in the Stuttgart Open. Zverev next faces American Steve Johnson, who defeated former champion Philipp Kohlschreiber 6-3, 6-3, while Khachanov awaits the winner between Jan-Lennard Struff and Laslo Djere.
STUTTGART, Germany — Matteo Berrettini beat Canadian teenager Felix Auger-Aliassime 6-4, 7-6 (11) to win the Stuttgart Open and his third tour-level title on Sunday.
The Italian saved five set points in a second-set tiebreaker and clinched his first title on grass. His other titles came at Budapest in April, and Gstaad, Switzerland, last year.
The 18-year-old Auger-Aliassime previously reached championship matches in Rio de Janeiro in February and the Lyon Open in May – both on clay.
Berrettini won all 50 of his service games during the week in Stuttgart. He did not face a break point against Auger-Aliassime.
Auger-Aliassime progressed to the final in his first professional grass tournament without playing Saturday as compatriot Milos Raonic withdrew ahead of their semifinal due to back problems.