In a matchup between two women who have reached the top spot of the WTA rankings, Iga Swiatek fended off Angelique Kerber 7-5, 6-3 to reach the Round of 16 at the Internazionali BNL d'Italia.

"For sure, wasn't easy," Swiatek said after her latest win. "I'm happy in important moments at the end of both sets I was ready to break. I got my focus up a little bit. At the end that's what made the difference, so I'm happy."

Swiatek, the current World No.1, needed all of her mettle to oust Germany's Kerber, who held the No.1 ranking for 34 weeks during her career. Kerber returned to tour this January following a yearlong maternity leave.

Swiatek, who won Rome in 2021 and 2022, prevailed over Kerber in 1 hour and 38 minutes on Monday. 

Now into her 103rd week ranked No.1, Swiatek improved to 3-0 against Kerber, including a victory at the German's comeback event at the United Cup at the start of the season. Swiatek also extends her lead as this year's current match-win leader with 33 victories on tour (Elena Rybakina is in second place with 30).

Next up: Swiatek will now face No.18 seed Madison Keys of the United States in the quarterfinals. Keys defeated No.28 seed Sorana Cirstea 6-2, 6-1 earlier on Monday, which was Keys' first win in three career meetings with Cirstea.

After rehabbing her shoulder for the first two months of the season, Keys is surging again and has won seven of her past eight matches. But her one loss in that timeframe was to Swiatek, who beat Keys 6-1, 6-3 in the Madrid semifinals just over a week ago.

"Playing against [Keys] is not easy," Swiatek said. "The most important thing is to stay focused and really disciplined. That's what I'm going to do for the next days."

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Match moments: On Monday, neither Swiatek nor Kerber was troubled on serve through 4-3, but Swiatek fired a forehand winner to break for 5-3 and serve for the set. Kerber, though, found some vintage groundstrokes to pull back on serve at 5-4.

Swiatek then held five set points on Kerber's serve in that game, but the German swatted away each of those chances.

Watch This: Kerber stuns Swiatek with a roaring hot shot in Rome

Kerber pulled off some more magic serving at 6-5, erasing another two set points as she clawed from 15-40 to deuce. However, a wide forehand error by Kerber gave Swiatek an eighth set point, and the Pole closed out the set at last after a netted error by Kerber.

Kerber edged ahead 2-0 in the second set, but Swiatek raised her level, cracking a backhand pass down the line to break back for 2-2. That break turned the tide completely back in Swiatek's favor as she eased home from there.

Swiatek finished the match with 32 winners to Kerber's 14, and the top seed also had one fewer unforced error than Kerber. Kerber saved nine of the 13 break points she faced -- seven of those being set points in the first set -- but she only broke Swiatek twice.