Australia's Nick Kyrgios beat world number three Alexander Zverev 6-3 6-4 to win the Mexican Open in Acapulco.
The 23-year-old started the week 72nd in the world - his lowest ranking in five years, but is expected to return to the world's top 30 after this win.
Zverev was the third top-10 player Kyrgios beat to reach the final, after victories over Rafael Nadal and John Isner and a win against Stan Wawrinka.
"I knew I was the underdog going in," he said. "I didn't expect much."
Kyrgios was handed a silver pear trophy and a black sombrero as he won his fifth ATP Tour title win.