An ice cold performance from Karen Khachanov has seen the Russian eliminate US Open favourite Nick Kyrgios 7-5 4-6 7-4 6-7(3) 6-4 to progress to the semi-finals at a major for the first time.
The 27th seed will meet Norway's fifth seed Casper Ruud for a spot in the final after outlasting a fighting Kyrgios in a magnificent match that spanned three hours and 41 minutes.
Khachanov came to play right from the beginning of the match and maintained his composure throughout as Kyrgios went through patches of dominance and disinterest.
The Australian looked close to retiring because of a knee injury in the first set and eventually lost the opener before fighting back to win the second set.
With Kyrgios seemingly recovered, Khachanov again lifted in the crucial moment in the third set to win that 7-5 before the fourth set went to a tiebreaker.
It was Kyrgios who stepped up in the clutch moments in the breaker to force a fifth and deciding set.
But when it was all on the line, Khachanov was the stronger player, breaking in the first game of the fifth set before riding out several break points on his serve to reach a Grand Slam semi-final.
Kyrgios performed at his highest levels in the back of the end of the match, but the Russian was too strong in the best win of his career.
Khachanov came within two points of victory while ahead 6-5 as Kyrgios served in the fourth set. Kyrgios held on there and dominated the ensuing tiebreaker to force a fifth.