Roger Federer's quest for an eighth Western & Southern Open title started with a routine victory over Juan Ignacio Londero.
Federer – the third seed – barely raised a sweat as he accounted for Londero 6-3 6-4 en route to the last 16 in Cincinnati on Tuesday.
The 20-time grand slam champion will face the winner of the match between Stan Wawrinka and Andrey Rublev at the ATP Masters 1000 tournament.
Federer lost to Novak Djokovic in last year's final, though the Swiss superstar holds the record for most Cincinnati titles with seven.
The 38-year-old stormed out of the blocks against Londero on Tuesday, racing out to a 3-0 lead after just seven minutes.
It was Federer's first appearance since his dramatic defeat at the hands of Djokovic in the Wimbledon decider but there were no signs of rust as he hit 10 winners in a dominant 22-minute first set.
Londero – more comfortable on clay – stepped it up in the second set before the rain arrived to halt proceedings, with the score level at 2-2.
After almost an hour off court, Federer returned in merciless fashion, breaking immediately as he cruised into the third round.