James Blake produced an electrifying display to shatter Rafael Nadal's title dreams in front of a raucous crowd packed inside Arthur Ashe stadium.
In the match of the US Open so far, the New Yorker triumphed 6-4 4-6 6-3 6-1.
The momentum looked to be with Nadal when he made it one set all but Blake raised his game to take the third, hitting 10 winners and just two errors.
The Spaniard wilted in the fourth and, after taking his first match point, Blake fell to his knees in disbelief.
"I can't say enough how this is a dream come true," Blake told the crowd.
"Rafael is a great champion. When I look back on my career, this will be one of my greatest wins.
"I can't believe how well things are going. I am waiting for the alarm clock to go off and I'm going to wake up - but I don't want to."
The 25-year-old goes through to the fourth round of a Grand Slam for the first time in his career where he will face 19th seed Tommy Robredo after he beat France's Sebastien Grosjean.
STATS: BLAKE v NADAL
6/8----Break pts won----2/10
Nadal, who has won nine titles this year including the French Open, praised Blake for his performance but blamed himself for the defeat.
"I feel bad because I played bad," said the 19-year-old.
"I was playing very bad in the first two rounds and I improved today, but I was still not at my best. The other thing is he played better.
"I just lost one of the best tournaments in the world, so I'm not very happy right now."
As expected, the match began as a war of attrition between two of the fastest and most powerful players on the circuit.
Games went with serve until the ninth game when a blistering Blake forehand and a net-cord in his favour gave the American wildcard two break points.
He gleefuly grabbed the first of those when Nadal hit a forehand approach too long and wrapped up the set in 43 minutes.
The American had break point in the opening game of the second set, but Nadal rallied to win six points in a row and take a 2-0 lead.
Nadal wilted in the fourth set as Blake raced through it 6-1
Urged on by a fiercely partisan crowd in the Arthur Ashe Stadium, Blake went on the attack again to break back with a string of winners.
But Nadal was beginning to establish himself and, having squandered break points in the eighth game, he took advantage of his third set point two games later to level the match.
The Spaniard looked the stronger early in the third but he was stunned when Blake broke serve for the third time to lead 3-2, clinching it with a crowd-pleasing top-spin lob.
A pumped-up Blake went on to break again to take the set, sealing it with an enormous smash he could have safely left.
The American was now in charge and he bagged the crucial break he needed in the fourth game of the fourth set taking it to love.
Blake broke again to lead 5-1 and he served out comfortably as Nadal crumbled in two hours 26 minutes.