Rafael Nadal cruised to victory in his first match since clinching a return to world number one while Alexander Zverev's 10-match win streak was halted at the WTA and ATP Cincinnati Masters.Nadal, a 15-time Grand Slam champion who captured his 10th French Open crown in June, defeated Richard Gasquet 6-3, 6-4, improving to 15-0 in ATP matches against the Frenchman.Gasquet hasn't taken a set off the 31-year-old Spaniard in 10 consecutive meetings since doing so at Toronto in 2008. Nadal was assured overtaking Britain's injured Andy Murray atop the rankings next week when Roger Federer withdrew Monday from Cincinnati with a back injury.Next for Nadal, who had a first-round bye, is a third- round matchup with 24th-ranked countryman Albert Ramos- Vinolas.On the women's side, top-ranked Czech defending champion Karolina Pliskova defeated Russian lucky loser Natalia Vikhlyantseva 6-2, 6-3, dropping Dane Caroline Wozniacki from the list of rivals who can overtake her for world number one this week.Romania's second-ranked Simona Halep and Ukraine's fourth-ranked Elina Svitolina — who ousted compatriot Lesia Tsurenko 6-1, 6-4 — could still swipe the top spot for the first time in their careers.Germany's third-ranked Angelique Kerber, who lost the top ranking after Wimbledon, lost her chance to reclaim it by falling to Russia's Ekaterina Makarova 6-4, 1-6, 7-6 (13/11).