Federer and Kyrgios, 21, were on Friday played an intense match that was decided in three tiebreakers, 7-6, 6-7, 7-6, while Nadal registered a confidence-boosting 6-1, 7-5 victory over Fognini to march into his fifth Miami final, reports Efe.
The Australian's force and momentum forced Federer to remain on the central court at Crandon Park for more than three hours, which could prove to be decisive during his final against Nadal.
Kyrgios increased pressure on Federer and broke his serve in the seventh game, after several errors on the Swiss player's part.
Later, in the next game, Kyrgios opted for two powerful serves that misfired, leading to a double fault that allowed Federer to draw level (5-5).
The tie-break lasted 72 minutes, during which Federer exercised his greatest self-control while the Australian seemed to lose it, as the Australian Open champion took the first set 11-9.
The next set too was decided through a tiebreaker and the Australian won the set 9-11, taking the match to the third set.
This setback did not affect the Swiss as it began with the scores level, whereas the young Kyrgios was once again up to the challenge as the set, as well as the match, drifted again towards a tiebreaker.
Eighteen-time Grand Slam champion Federer emerged to be the winner (7-5), holding his nerves and taking advantage of his opponent's double fault at one of the most crucial parts of the game.
"It did feel very good, because you don't very often play three breakers in a match. It's nice to win those and winning breakers is always such a thrill," Federer told ATP website.
"It's great winning this way, especially because I remember the loss against him a few years ago, It was rough. It was the birthday of my boys. I wasn't with them and had that match, so it was nice to get this one tonight."
In the other semi-final, Nadal put in a workmanlike performance, relying on his solid ground strokes against an opponent who committed a whopping 38 unforced errors and appeared to be battling an injury.
Fognini also seemed listless at times on an afternoon when the temperature climbed to 29 C (84 F), the hottest day of the tournament.
The Spaniard earned the first service break of the match in the fourth game thanks to a Fognini double fault and three errors and a second one when the Italian squandered a 40-0 lead in the sixth game.
He then wrapped up the first set in just 25 minutes with an easy service hold.
Fognini put up more of a fight in the second set, staving off five break points in his first two service games to stay even until 5-5.
But he lost his serve a third time in the match when the wind pushed what appeared to be a perfect drop shot wide of the sideline.
The fifth seed, who did not face a single break point, lost only nine points overall on serve throughout the hour-and-a-half match and only three of his 15 second-serve points.
The unseeded Fognini, by contrast, paid the price when having to put in a second serve, losing more than two-thirds of those points.
Those numbers were a reflection of the solid baseline play of Nadal, who committed just 12 unforced errors in the contest while striking the ball with sufficient aggressiveness to keep Fognini from getting into an attacking position.
The win was Nadal's third straight victory over the Italian, who came from two sets down to stun the 14-time Grand Slam champion at the 2015 US Open and had won three of their previous six matches.
The two also got into a spat at the 2015 Hamburg event, where Fognini complained that Nadal was taking too much time between serves and yelled out "don't break my balls" at the Spaniard during a changeover.
The 30-year-old Spaniard pulled out that match in two close sets, but he showed in Friday's win that he is in much better form than two years ago.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
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