Three-time Grand Slam finalist Ons Jabeur withdrew from the Mubadala Citi DC Open on Thursday, giving the United States' Robin Montgomery a walkover victory in the second round.

Jabeur, a Tunisian who was the event's fourth seed, wrote in a statement, "Regrettably, I must withdraw from the Mubadala Citi DC Open due to a shoulder injury I have recently sustained. After consulting with my doctor, it has been determined that participating will aggravate my condition."

Another Thursday match didn't go the distance, as third-seeded Russian Liudmila Samsonova retired after losing the first set 6-2 to Spain's Paula Badosa.

Next up for Badosa is a quarterfinal match against Great Britain's Emma Raducanu.

Sixth-seeded Victoria Azarenka of Belarus defeated China's Wang Yafan 6-1, 6-7 (5), 6-3, and the Czech Republic's Marie Bouzkova posted a 7-5, 7-6 (8) win over the United States' Taylor Townsend.

--Field Level Media