Roger Federer survived a brave challenge from American qualifier Frances Tiafoe before emerging with a 7-6 (7/2) 6-3 victory as he got his Miami Open title bid underway on Saturday. Tiafoe, ranked 101st in the world, struggled against Federer's serve but was strong on his own and forced a first set tie-break in which the Swiss came out on top.
The 19-year-old son of immigrants from Sierra Leone then broke Federer's serve in the first game of the second set only for the 18-times Grand Slam winner to break back twice and run out a comfortable winner in the end.
Federer was full of praise for his opponent and said he would have gained valuable experience from the contest.
"I hope he's going to learn a lot from a match like this just because playing on a centre court with a lot of people, under pressure, saving break points, making break points, playing breakers. That's what it's about, and it should feed a player like him with a lot of energy moving forward," he said.
Federer is in fine form having clinched the Australian Open and Indian Wells so far this year and extended his record to 14-1.
The 35-year-old is looking for his third Miami title following wins in 2005 and 2006.
Federer should have met Del Potro in Miami last year but the Swiss had to pull out with an illness and he says he is looking forward to renewing his rivalry with the South American
Reigning US Open champion Stan Wawrinka got off to a solid start, beating Argentina's Horacio Zeballos 6-3, 6-4 at Crandon Park on Saturday.
Wawrinka will face either Malek Jaziri next after the Tunisian beat Feliciano Lopez 6-3, 4-6, 6-3.
Australia's Nick Kyrgios also progressed on Saturday enjoying a 6-4 6-3 win over Bosnian Damir Dzumhur.