Serena Williams and Angelique Kerbe, battling it out for the world number one ranking, are the first two women to qualify for the season-ending WTA Tour Finals in Singapore, the WTA said on Monday.
 World number one Williams, who leads Kerber by 190 ranking points, has won the title five times but missed last year’s event through injury.
 Kerber, who won her first grand slam title at the Australian Open in January and who reached the final at Wimbledon, will be making her fourth appearance in the October 23-30 event, reserved for the top eight-ranked players of the year.
 “I’m very proud and excited to qualify for the BNP Paribas WTA Finals in Singapore,” said American Williams, who will try to break the Open-era record of 22 grand slam singles titles she shares with Steffi Graf by winning the US Open which starts next week.
 Fresh off her runner-up finish at the Western & Southern Open in Cincinnati, Kerber has secured her fourth appearance at the WTA Finals. Her first two appearances at the event were in Istanbul, Turkey, in 2012 and 2013—highlighted by her win over then-No. 4 Agnieszka Radwanska—followed by last year’s showing in Singapore, where she beat eventual runner-up Petra Kvitova in the round-robin stage.
This year Kerber will be bidding to advance to the semifinals for the first time, after being only one set away from doing so in 2015.
Twenty-eight-year-old Kerber has enjoyed her best season yet, compiling a 47-14 record, and reaching a career-high ranking of
 “It is one of the most important events of the year and we all fight to qualify in the top eight,” Germany’s Kerber said in a statement released by the WTA. “I have great memories from my other experiences at the tournament and I hope to play some great matches and win the title.”