World number one Novak Djokovic was beaten by 20-year-old lucky loser Luca Nardi in round three at Indian Wells.
Italian Nardi, ranked 123 in the world, had originally being knocked out in qualifying but reached the main draw after another player's withdrawal.
He hit 34 winners in a 6-4 3-6 6-3 win over the 24-time Grand Slam champion, converting match point with an ace.
"It's crazy," said Nardi, the lowest-ranked player to beat Djokovic at ATP Masters 1000 or Grand Slam level.
"I don't know [how I held my nerve], I think it is a miracle, because I am a 20-year-old guy, and beating Novak.