The 25-year-old American breezed to a 6-2 6-2 win over the outplayed Italian, claiming the first two games in both sets to set the tone.
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After Giorgi fought back to 3-2 in the first set, Pegula took the next three games as the Italian's errors mounted in the 59-minute match.
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The second set was even more one-sided as Pegula marched to a 5-1 advantage before Giorgi, on the comeback trail after wrist and ankle injuries, won a second game.
Pegula, the daughter of the owners of the National Football League's Buffalo Bills and National Hockey League's Buffalo Sabres, closed out the match with a stunning service winner and sank to her knees in celebration.
She won 81% of her first serves and saved the only break point she faced against the former Wimbledon quarter-finalist.
“I’ve always played so well here,” Pegula told the crowd afterwards.
“So I’m so happy I can get my first title here.”
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