Unseeded Italian Fabio Fognini upset second ranked Kei Nishikori 6-4, 6-2 on Wednesday to earn a Miami Open semi-final clash with Rafael Nadal.
The 29-year-old world number 40 was the only unseeded player left in the last eight but showed no hint of nerves as he took the game to his Japanese opponent from the outset.
It was the Italian's first victory in three attempts over Nishikori and his first Masters series quarter-final win since 2013, when he reached the last four in Monte-Carlo.
Fognini now faces Nadal in the semi-final after the Spaniard brushed aside Jack Sock in straight sets, winning 6-2, 6-3 to stay on track for a first ever Miami Open crown.
Nishikori earlier said he had not felt fully in top shape for the contest.
"I wasn't 100%, physically, I mean, it was tough conditions for me," he said, referring to the heat on the mid-afternoon Key Biscayne centre court.
"But it was also same for him, too. He was playing a lot of the long matches, but I think he still played good enough to beat me today," he added.
Fognini, who was cheered on by his friend, former Italy footballer Christian Vieri, said he had come through a demanding test.
"It wasn't easy and I was just focused on my game. I am very happy, I'm in the semifinal, I'm playing well and I feel good again on the court," he said.
Nadal meanwhile looked in ominous form as he neutralised sock in one hour and 22 minutes.
The Spaniard was able to save six of seven break points earned by Sock as he kept control of the contest.
The 30-year-old Spaniard has never won in Miami despite being a four-time finalist, and his win opens up the possibility of a meeting in the final with his long-standing rival Roger Federer.
On Thursday, Federer takes on Czech tenth-seed Tomas Berdych while the last quarter-final pits Germany's Alexander Zverev against Australia's Nick Kyrgios.