Cincinnati (US), Aug 17 : In a showdown between former Grand Slam champions, No.4 seed Elena Rybakina of Kazakhstan held off Latvia's Jelena Ostapenko 6-7(6), 6-2, 6-4 on Wednesday to make the Round of 16 at the Cincinnati Masters. Last year's Wimbledon champion Rybakina took 2 hours and 17 minutes to pull off the come-from-behind victory on Wednesday night and edge ahead 3-2 in her head-to-head with 2017 Roland Garros titlist Ostapenko. Rybakina will face Italian qualifier Jasmine Paolini on Thursday for a quarterfinal spot. Paolini defeated fellow qualifier Cristina Bucsa of Spain 6-1, 6-3 earlier on Wednesday. On the other hand, World No.2 Aryna Sabalenka was also pushed to three sets in her opener, holding off No.192 Ann Li 7-5, 2-6, 6-4 to advance in 2 hours and 3 minutes. A semifinalist last year, Sabalenka struggled against Li's all-court game before steeling herself in the third set to wrench back control of the match and get the win. The Australian Open champion will next face Daria Kasatkina in the round of 16 on Friday. Meanwhile, World No.1 Iga Swiatek defeated 34th-ranked Danielle Collins for the second time in less than a week with a 6-1, 6-0 victory in the second round of the Western & Southern Open on Wednesday. Swiatek needed just 59 minutes to beat former World No.7 Collins for the fourth time in their five meetings and booked her spot in the Cincinnati Round of 16 for the second straight year, where she will lock horns with Chinese player Qinwen Zheng. The Pole is currently enjoying her 72nd week at World No.1, an unbroken stretch since she first ascended to that position on April 4, 2022. It is the 10th-longest streak at World No.1. Only two women have held the No.1 ranking for more consecutive weeks in their first stint at No.1 -- Stefanie Graf (186 weeks) and Martina Hingis (80 weeks). /IANS