RIYADH, Saudi Arabia -- World No.4 Jasmine Paolini made a winning debut at the WTA Finals Riyadh presented by PIF, defeating No.5 Elena Rybakina 7-6(5), 6-4 on Day 1. 

With the victory, Paolini joined World No.1 Aryna Sabalenka atop the Purple Group with a 1-0 record. She also improved to 3-2 against Rybakina.

Three takeaways from Paolini's first career win at the WTA Finals:

Paolini's poise: The 28-year-old Italian is the second-oldest player to make her WTA Finals debut, trailing only Li Na, who was 29 in 2011. But in a season of first-time milestones, Paolini was once again unfazed by the moment. Not even a prematch meeting with Brazilian football star Neymar could rattle the affable Italian. 

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Paolini and Rybakina split their two meetings this season, both coming on clay and both going a full three sets. Paolini won the most consequential showdown, a gritty win in the Roland Garros quarterfinals en route to her first major final. 

Facing down Rybakina for the first time since, Paolini broke first to lead 4-2 before handing back the break immediately to give the 2022 Wimbledon champion a boost of confidence. The two traded holds to take the opener into a tiebreak, where Paolini's match toughness helped her surge to take the lead. 

Having held off Rybakina in the edgy first set, Paolini dominated the second to seal the 1-hour and 44-minute win. In an impressive stat that underlines Paolini's remarkable poise in 2024, only two players have won more tiebreaks than the Italian this season. Paolini won her 11th tiebreak, behind only Jessica Pegula (12) and Linda Noskova (13). 

Rybakina's rust: Paolini is the only player to qualify in both singles and doubles this season, and Saturday's match was her 104th of the season. In contrast, Rybakina was playing just her third match since making the Wimbledon semifinal and her first since the US Open. 

Rybakina looked sharper than expected for much of the first set, but the rust began to show on crucial points and as the match wore on. She struck 56 unforced errors in the match and converted just one of five break points. 

Before the tournament, Rybakina said she came into Riyadh with low expectations, but was hopeful she could play herself into both form and confidence. Still, there were positives for Rybakina to take away from the match, as she readies to take on No.1 Sabalenka. Despite serving at just 50 percent, she fired eight aces and struck 27 winners compared to Paolini's 12. 

Zheng bests Paolini in Wuhan to make back-to-back semis on home soil

Paolini faces a tough test: There's no time to rest for Paolini. Not only will she begin her doubles campaign with Sara Errani on Sunday, but she'll need to prepare for World No.7 Zheng Qinwen on Monday. 

Zheng lost in straight sets in her opener to Sabalenka, but the Chinese No.1 is 3-0 against Paolini, including a three-set win a few weeks ago in Wuhan. It's a tough match-up for Paolini, who will then face Sabalenka in her final round-robin match.