Ready or not—Day Two is upon us! Here are some of the matches to watch as first-round play wraps up and second-round play kicks off in Cincinnati.
 Roger Federer vs Peter Gojowczyk
Roger Federer will make his grand return to the Western & Southern Open on Tuesday night, after missing the event the past two years due to injury. The seven-time champion will open his 2018 campaign with a first-time opponent in Germany’s Peter Gojowczyk. Federer last played at Wimbledon, where he lost a marathon five-set match to Kevin Anderson in the quarterfinals. Make sure to check out Federer’s media day thoughts on Facebook.
Serena Williams vs  Petra Kvitova
The last time Serena Williams played in Cincinnati, she left holding the trophy after taking out Simona Halep in the 2015 final. On Monday, she took one step closer to a repeat performance with a commanding 6-1, 6-2 win over Daria Gavrilova. The two-time Cincinnati champion will meet Petra Kvitova in the second round, facing off for the first time since 2015. Kvitova won their last meeting, but it’s Williams who holds the 5-1 head-to-head advantage. With five titles in 2018 alone, Kvitova, 28, is a dangerous opponent no matter who she faces. Get ready for a fun one.
Stefanos Tsitsipas vs  David Goffin
All aboard the Tsitsipas train! Fresh off reaching the Toronto final after taking out four consecutive top-10 players, Greece’s Stefanos Tsitsipas is looking to keep the ball rolling at the Western & Southern Open. Ranked 159 in the world just one year ago, 20-year-old Tsitsipas debuted at a career-high No. 15 on Monday. To keep his magical summer run alive, he’ll need to get another win over Belgium’s David Goffin – a player he upset just weeks ago in Washington, D.C. Assuming he’s gotten some rest after his success in Canada, Tsitsipas is poised for a repeat performance.
Naomi Osaka vs Maria Sakkari
Tuesday’s showdown between rising stars Naomi Osaka and Maria Sakkari has potential to be one of the matches of the tournament. Only 20 years old, Osaka made her WTA Tour breakthrough at Indian Wells this year, where she captured the title as an unseeded player. Sakkari, too, had a strong spring run in the desert, where she reached the fourth round. But it was in San Jose just two weeks ago that the 23-year-old Greek upset Venus Williams en route to her first WTA Final. Whose fire will burn brighter on Tuesday?
 Karolina Pliskova vs Agnieszka Radwanska
Upon first glance, this matchup would seem to favor the Czech Republic’s big-hitting baseliner, Karolina Pliskova. The 26-year-old has played some of her best tennis in the past two years, rising to world No. 1 after her championship run here in Cincinnati in 2016. Radwanska, by comparison, sat out two months of 2018 with a back injury, sliding to No. 38 in the world. But it’s Radwanska – the crafty 2012 Wimbledon finalist – who might have the advantage. She has a perfect 7-0 record against Pliskova, with her last win over coming at the 2016 WTA Finals in Singapore. Who comes out on top?
Karen Khachanov vs Albert Ramos-Vinolas
Stefanos Tsitsipas wasn’t the only player with a breakthrough in Toronto. Russia’s Karen Khachanov, 22, reached his first Masters 1000 semifinal and notched wins over Pablo Carreno Busta and world No. 9 John Isner. As a result, Khachanov made his top 30 debut on Monday. He will look to get his third career win over Spain’s Albert Ramos-Vinolas, but each of their three previous matches has made its way to three sets. The battle is on.