The seventh-seeded Bulgarian advanced to his eighth ATP World Tour Masters 1000 quarter-final with a 6-3, 7-5 victory over Del Potro, who struggled with the intense heat in the closing stages of the one hour, 39 minute match.
Nadal, who got a first-round bye, defeated Richard Gasquet 6-3, 6-4 to advance.
Rafael Nadal was made to wait before his second-round Rogers Cup match due to several rain delays but did his part to put the schedule back on track with a speedy 6-2 6-3 win over Frenchman Benoit Paire on Wednesday.
Federer, who skipped the entire clay court season after winning the Australian Open and claiming titles at Indian Wells and Miami this year, will next play defending champion Florian Mayer who beat Frenchman Lucas Pouille in three sets.
A summary of sports events and persons who made news on Monday
IMAGES from Day 6 at Wimbledon on Saturday.
IMAGES from matches played at the Miami Masters in Key Biscayne, Florida
The lanky wild card kissed the Montreal court after completing a rousing 3-6, 6-4, 7-6(4) triumph as the 18-year-old became the youngest player to ever reach the quarter-finals of an ATP Masters 1000 event.
Images from Day 7 of the 2019 French Open in Paris on Saturday.
Summary of sports events and persons who made news on Tuesday
India's Leander Paes and his German partner Alexander Zverev went down to the Spanish duo of Feliciano Lopez and Marc Lopez in a men's doubles first round match to bow out of the Cincinnati Open.
Images from matches played on Day 4 of the Australian Open at Melbourne Park on Thursday