Watch List: ATP's top 20 in Shanghai; Top women play for Singapore spots

This week, the focus is on the WTA's Road to Singapore in Hong Kong, Tianjin and Linz, and the Shanghai Rolex Masters, where the ATP's top 20 are in action.

The Watch List highlights the must-know storylines for the upcoming week in tennis. This week, the focus is on the WTA's Road to Singapore, where five spots remain in the eight-player field at the year-end championships. Venus Williams, Lucie Safarova, Agnieszka Radwanska, Angelique Kerber, and Flavia Pennetta are among the top contenders who are playing this week. In addition, the entire ATP Top 20 is in Shanghai, China, this week for the eighth Masters tournament of the year. 

Prudential Hong Kong Tennis Open​ (Hong Kong, China)

[Complete draw]

After Garbine Muguruza won the China Open in Beijing on Sunday, she pulled out of the Hong Kong open citing an ankle injury, which shuffled the draw in Hong Kong. With her withdrawal as the top seed in the tournament, Venus Williams takes her place as No. 1, Sam Stosur takes Venus's spot as the No. 3 seed and Heather Watson replaces Stosur in the No. 5 spot. No. 2 seed Angelique Kerber received a wildcard into the event and can still qualify for the WTA Finals, and she will open against Francesca Schiavone. In addition to Muguruza, Victoria Azarenka, Eugenie Bouchard, Zarina Diyas, Sabine Lisicki, Ajla Tomljanovic and Coco Vandeweghe also pulled from the event. Daria Gavrilova, Caroline Garcia and Alize Cornet are also players to watch in the field. 

Nadal is determined to stay calm, motivated despite the storm of 2015

​Generali Ladies Linz (Linz, Austria)

[Complete draw]

Lucie Safarova, who has already qualified in doubles for the WTA Finals in Singapore with partner Bethanie Mattek-Sands, looks to secure a spot in singles as the top seed in Linz. Caroline Wozniacki is the second seed but is out of contention for the year-end championships. She opens against Mirjana Lucic-Baroni, while Safarova starts off against Andreea Mitu and third-seeded Roberta Vinci will play a qualifier in the first round. Andrea Petkovic, Anna Karolina Schmiedlova, Camila Giorgi, Anastasia Pavlyuchenkova and Barbora Strycova are also in the field. 

Tianjin Open (Tianjin, China)

[Complete draw]

U.S. Open champion Flavia Pennetta is the top seed in Tianjin, where she can secure a spot in Singapore with a run. No. 2-seed Agnieszka Radwanska kept herself in the running for a spot in the WTA Finals with a semifinals run at the China Open and she'll open against a qualifier in Tianjin. In last year's final, No. 7-seed Alison Riske beat Belinda Bencic for the title, and in this year's tournament, Riske could face Radwanska in the quarterfinals. Also in the field are 2014 Generali Ladies Linz champion Karolina Pliskova, Kristina Mladenovic, Teliana Pereira and up-and-comer Zheng Saisai. On Monday, Elena Vesnina upset fourth-seeded Elina Svitolina to advance to the second round. 

Djokovic beats Nadal for 6th China Open title

Shanghai Rolex Masters (Shanghai, China)

[Complete draw]

With 1,000 points up for grabs, the ATP's Race to London could see a major shift this week in Shanghai, where the entire top 20 is in action. No. 1 and China Open champion Novak Djokovic leads the field, joined by defending champion Roger Federer, Andy Murray, Tokyo Open champion Stan Wawrinka, Tomas Berdych and Kei Nishikori. Murray, who has already qualified for London, is playing in his first tournament since a fourth-round loss to Kevin Anderson at the U.S. Open. China Open runner-up Rafael Nadal is also in the field, along with David Ferrer, Milos Raonic and Gilles Simon. Some notable match-ups include Nadal vs. Ivo Karlovic, Nishikori vs. Nick Kyrgios, Ferrer vs. Bernard Tomic and Murray vs. Steve Johnson.