Juan Martin del Potro advanced to the third round of the Shanghai Rolex Masters following a 6-3, 6-4, win over 19-year-old Russian Andrey Rublev Tuesday. Seeded 16th in the tournament, del Potro never faced a break point and hit 14 aces to beat Rublev in their first career meeting and arrange a third-round clash against either No. 3 seed Alexander Zverev or Aljaz Bedene, who defeated Paolo Lorenzi. Fabio Fognini also reached the third round via a 7-6(7), 6-3 upset win over No. 15 seed Lucas Pouille. Fognini saved three break points and hit nine aces to improve to 2-1 against Pouille.

Fognini will next face the winner of the showdown between top seed Rafael Nadal and American Jared Donaldson.

Fourth seed Marin Cilic improved his chances of making it to the Nitto ATP Finals in London after beating Kyle Edmund, 6-3, 7-6(5), in his opening match in Shanghai. Cilic, currently in sixth place in the Emirates ATP Race To London, will qualify for the season-ending tournament if he bags the Shanghai title. Cilic saved all three break points en route to victory over Edmund in one hour and 38 minutes. In the third round, he will face either Chinese wild card Di Wu or American Steve Johnson, who advanced to the second round after No. 13 seed Nick Kyrgios retired after losing the first set, 7-6 (5).

Wozniacki beats Bouchard in Hong Kong

Defending champion and third seed Caroline Wozniacki cruised past Eugenie Bouchard, 6-1, 6-1, Tuesday in the opening round of the Hong Kong Tennis Open. Wozniacki, who won 10 straight games at one point, needed just 55 minutes to dispose of the Canadian. In the second round, Wozniacki will take on Australian Lizette Cabrera.

Top seed Elina Svitolina booked a spot in the second round after beating Zarina Dayas in straight sets in one hour and 40 minutes, while second seed Venus Williams downed Risa Ozaki, 6-2, 6-2. Williams will next face another Japanese in Naomi Osaka, who defeated Chile qualifier Alexa Guarachi, 7-5, 6-4.

In other matches, fourth seed Agnieszka Radwanska advanced to the next round with a three-set triumph over Zhang Ling; Luksika Kumkhum stunned fifth seed Elena Vesnina, 6-3, 6-4; sixth seed Anastasia Pavlyuchenkova beat Timea Babos in two sets; and Daria Gavrilova ousted Miyu Kato, in straight sets.

Simona Halep grabs No. 1 ranking

Steve Simon, WTA Tour CEO, congratulated Simona Halep of Romania for claiming the No. 1 spot after latest rankings came out Monday. Halep grabbed the No. 1 spot from Garbine Muguruza, who held the No. 1 spot for four straight weeks after the US Open. Halep became the first Romanian to reach the top spot.