Marcos Giron has taken down the top seed…

The 30-year-old Colombian American tennis player, ranked 67th in the world, stunned Frances Tiafoe, the No. 1 seed, 6-1, 6-4 on Friday night to reach the semifinals of the Dallas Open.

It’s the the second time in three years that Giron has advanced to the semifinals at the hardcourt event, which takes places on the SMU campus.

Giron, unseeded in the tournament, stunned Tiafoe early and rolled a win over the highest-ranked player in the field at No. 14.

It’s Giron’s 12th win over a top-20 opponent.

He’s still seeking his first ATP Tour title.

He’d lost to Tiafoe 6-2, 6-2 at Indian Wells almost a year ago.

“I was excited to play him again,” said Giron, who won the first three points on each of Tiafoe’s first two service games on the way to a 5-0 lead. “Margins are thin. I knew that I was playing well.”