ROME -- Elena Rybakina is discovering that her big serve and heavy groundstrokes can do damage on clay courts, too.
The Wimbledon champion was a dominating 21-9 with winners when Ukrainian opponent Anhelina Kalinina retired due to a left thigh injury early in the second set of the rain-delayed Italian Open final on Saturday.
"I can play good on all the surfaces," Rybakina said. "It's just maybe for clay I need to be ready more physically and maybe have a lot of preparation."
It's been quite a year for Rybakina, who reached the final of the Australian Open, also won an elite title in Indian Wells and was the runner-up in Miami.
"I'm proud that I can maintain this level," she said. "I can see improvements on the court, physically also. ... I think there is still a lot of room to improve."
On Monday, Rybakina will move up to a career-high No. 4 in the rankings and will be a contender at the French Open, which starts next weekend.
"She's serving 200 kph [125 mph]. She's also making winners like no one on tour," Kalinina said. "Anyone can win in Paris, but she has good chances.
"I am sure if she's going to do like this, maybe new world No. 1 for sure."
Rybakina was leading 6-4, 1-0, 15-0 when Kalinina called for a trainer and grasped her left leg as she teared up. She then decided she couldn't continue.
The final began at almost 11 p.m. on Saturday and Rybakina lifted the trophy after midnight on Sunday.
"I'm really sorry that I couldn't play," Kalinina said during the awards ceremony as the crowd -- which had waited under the rain for hours before the night session started -- whistled.
Rybakina earned her biggest title on clay. Her only other trophy on the surface came in Bucharest in 2019.
The 47th-ranked Kalinina was playing in the biggest final of her career and has been dedicating her performances to her war-torn country.
Kalinina's family home was destroyed in a Russian attack last year. Also, her elderly grandparents have had to relocate from the southern city of Nova Kakhovka -- which is held by Russian forces -- to Kyiv. Kalinina's parents work as tennis coaches in Kyiv and she said on Friday there was a "huge, huge bomb near them, near their academy" a few days ago.
Rybakina was born in Moscow and has represented Kazakhstan since 2018, when that country offered funding to support her tennis career.
Kalinina spent more than four hours longer on court than Rybakina entering the final, having won the longest match on the women's circuit this season -- 3 hours, 41 minutes against Beatriz Haddad Maia in the quarterfinals. She also required three sets to beat Russia's Veronika Kudermetova in an emotionally charged semifinal.
"I feel like I am at my physical limit today," Kalinina said.
Top-ranked Iga Swiatek also retired in the third set against Rybakina in the quarterfinals due to a right thigh injury.
The Associated Press contributed to this report.