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Australia's Cruz Hewitt jumped 255 spots to number 357 in the ATP live rankings after his win in the round of 32 at the DC Open. (Getty Images: Emilee Chinn)

Teenage Australian tennis player Cruz Hewitt has jumped more than 250 spots in the ATP world rankings after his first Tour win at the DC Open.

After warming up with father Lleyton, the 17-year-old Hewitt defeated former world number 37 Marcus Giron in straight sets.

Hewitt will next play either Alex de Minaur or Stefanos Tsitsipas in the round of 16.

Cruz Hewitt's victory in his ATP Tour main-draw debut is set to rocket the son of a gun up the world rankings.

Fresh off a run to the Wimbledon boys final, Hewitt beat former world number 37 Marcus Giron — currently ranked 85 — 6-3, 6-4 in Washington DC on Tuesday (Wednesday AEST).

The Australian, who didn't face a break point, became the fourth man born in 2008 or later to win a tour-level match and the youngest Washington match-winner since Japan's Kei Nishikori in 2007.

The teen qualified thanks to walkovers after leading both Dusan Lajovic and top-seed Zach Svajda and has surged 255 places to number 357 in the ATP's live rankings.

He'll play the winner of countryman and mentor Alex de Minaur and former world number three Stefanos Tsitsipas in the next round.