Canada's Leylah Fernandez overcame 20 aces and saved two match points before beating fourth seed Elena Rybakina of Kazakhstan 3-6, 7-6 (3), 6-4 in second-round action Thursday at the Cincinnati Open.

But Fernandez, from Laval, Que., came back to get the break and win the ensuing tiebreaker, then didn't face break point in the third set as she closed out the match in two hours 35 minutes.

Rybakina, who missed the Paris Olympics and last week's National Bank Open in Toronto with acute bronchitis, looked rusty in her return with 17 double faults.

WATCH | Fernandez pulls off upset of Rybakina:

Fernandez upsets Rybakina in 2nd round of Cincinnati Open

Leylah Fernandez from Laval, Que. defeats fourth seed Elena Rybakina of Kazakhstan 3-6, 7-6 (3), 6-4 and advances to the third round of the Cincinnati Open. Fernandez claims her first win over a top-5 opponent since her run to the 2021 U.S. Open final. Rybakina had 17 double faults, including two on both of her match point opportunities.

It was Fernandez's first win over a top-5 opponent since her run to the 2021 U.S. Open final. She will next face NBO finalist Diana Shnaider of Russia.

Later Thursday, Montreal's Felix Auger-Aliassime was scheduled to face seventh seed Casper Ruud of Norway in a men's second-round match.