Roger Federer remained on course for back-to-back Masters titles with a 7-6 6-3 victory over American teenager Frances Tiafoe at the Miami Open.
Federer was given a thorough examination in his first meeting with the 19-year-old but despite Tiafoe's admirable effort, the Swiss great proved too strong to book his third-round spot and a possible meeting with Juan Martin del Potro if the Argentine can see off Robin Haase
Despite the gulf in experience between the players, Tiafoe underlined his status as one of the brightest talents in the game with a spirited display full of huge potential and winners off both wings.
But when he needed to, Federer found the extra gear that has brought him back to the very top of the game this year after his injury problems of 2016 and, after claiming the first set tie-break, eventually eased through the second set having got the measure of Tiafoe's serve.
The 35-year-old followed up a magnificent triumph at the Australian Open for Grand Slam number 18 with victory over Stan Wawrinka at Indian Wells last week and he remains on course for a first Miami title in more than 10 years.
After been given a first-round bye, Federer took to the Stadium Court at Crandon Park for the first time since losing to Kei Nishikori in the quarter-final in 2014 having missed the last two years in Florida.
Serving first, Tiafoe delighted the home crowd by more than holding his own with a string of impressive holds and big forehand winners.
Tiafoe, who lives in Florida but was born in Maryland after his parents moved to the United States from Sierra Leone, kept his nose in front throughout the set but offered little threat on the Federer serve and the inevitable result was a tie-break.
Federer forced the mini-break immediately, and despite an admirable effort from Tiafoe at 3-2 to break back, he unveiled his full array of shots to close out the breaker and seal the set.
Having been forced to run almost double the distance of Federer in the opener, it would have been easy for Tiafoe to cower but a blistering winner set him on his way to his first break points and he needed just one of them to lead the second set.
However, Federer, champion in Miami in 2005 and 2006, broke back immediately and went on to win the set 6-3 to move into the last 32
Elsewhere, John Isner, 2015 semi-finalist and 18th seed, beat Brazil's Thomaz Bellucci 7-5 7-6 and he will next face Alexander Zverev, who needed just an hour to beat Yen-hsun Lu 6- 6-3.