World number two Roger Federer, bidding for his eighth Cincinnati Masters title, outlasted Leonardo Mayer of Argentina 6-1 7-6(6) in the third round on Friday.
Playing in his first tournament since Wimbledon, Swiss Federer lost just four first-serve points and did not face a break point in the match.
Mayer had a chance to force a third set, but Federer held on to win his third consecutive meeting with the Argentine as players double up in matches in the rain-delayed tournament.
Federer will face compatriot Stan Wawrinka in the quarter-finals later on Friday.
Wawrinka beat Marton Fucsovics of Hungary 6-4 6-3 in their third-round match.
"ItвЂ™s been a while since IвЂ™ve played two matches in one day. Apparently it was 2004," Federer told ESPN. "I did play a lot of practice twice a day so if I wonвЂ™t be ready for today, IвЂ™ll never be ready.
"Playing against Stan obviously is a treat. Ten years ago and two days ago we won the Olympic gold together and weвЂ™re still playing... I'm very excited to play against him and itвЂ™s great for him, IвЂ™m happy to see him back again."
Mayer's compatriot Juan Martin del Potro and Serb Novak Djokovic also advanced.
Fourth seed Del Potro overcame Australian Nick Kyrgios 7-6(4) 6-7(6) 6-2 and former world number one Djokovic, the 10th seed, ousted defending champion Grigor Dimitrov of Bulgaria 2-6 6-3 6-4.
Del Potro will play Belgian David Goffin in the quarter-finals.
Goffin did not face a break point in defeating sixth seed Kevin Anderson of South Africa 6-2 6-4 in 76 minutes.
Djokovic returned to the court after rain halted play on Thursday with a break lead in the third set and completed the win.
He will take on Canadian Milos Raonic in the quarter-finals, also on Friday.
Former Cincinnati champion Marin Cilic survived a rain-delayed three-setter, the Croatian battling past Toronto semi-finalist Karen Khachanov 7-6(5) 3-6 6-4.
France's Gael Monfils overcame a determined Stan Wawrinka to win the Rotterdam Open 6-3 1-6 6-2 on Saturday, lifting his first title since January 2018.
Three-times Grand Slam champion Stan Wawrinka battled past Kei Nishikori 6-2 4-6 6-4 at the ABN AMRO World Tennis Tournament in Rotterdam on Saturday to set up a final against Frenchman Gael Monfils.
Former world number one Maria Sharapova will miss next month's BNP Paribas Open at Indian Wells due to a right shoulder injury, organisers said on Wednesday.
Stan Wawrinka knocked out fourth seed Milos Raonic and Damir Dzumhur ousted third seed Stefanos Tsitsipas on a day of surprises at the ABN AMRO World Tennis Tournament in Rotterdam.
Kei Nishikori overcame Pierre-Hugues Herbert 3-6 6-1 6-4 at the Rotterdam Open on Tuesday on his return from the knee injury which forced him to retire during his Australian Open quarter-final against Novak Djokovic.
Former French Open champion Jelena Ostapenko overcame strong winds and a determined Mihaela Buzarnescu to advance to the second round of the Qatar Open with a 6-1 4-6 6-2 victory on Tuesday.
Jo-Wilfried Tsonga beat fellow Frenchman Pierre-Hugues Herbert 6-4 6-2 to win the Open Sud de France in Montpellier and claim his first ATP title since 2017 on Sunday.
Jo-Wilfried Tsonga came from a set down to edge a gruelling quarter-final encounter with fellow Frenchman Jeremy Chardy at the South of France Open.
Gael Monfils doled out another lesson in outstanding tennis, winning 93 percent of points on his first serve, as he reached the semi-finals of the Sofia Open on Friday with a 6-3 7-6(5) win over GreeceвЂ™s emerging talent Stefanos Tsitsipas.