Retiring great Caroline Wozniacki is just one tournament away from the end of her career after she was denied a place in the final of Auckland’s ASB Classic by unseeded American Jessica Pegula.

Pegula came from a set down to defeat the former world No.1 in Saturday’s semi-final, winning 3-6 6-4 6-0 in one hour and 53 minutes.

The 25-year-old will play a third career WTA final on Sunday, facing legendary 23-major winner Serena Williams or emerging talent Amanda Anisimova.

Pegula banished early inconsistencies to rout her more credentialed rival in the third set and complete the surprise win.

“Caroline has had an amazing career and I know she’s retiring, so I’m glad I got to play her,” she said.

“I definitely knew that if I was going to play defensive, I was not going to win that battle. I had to step in and take my chances and trust my game.”

While Pegula’s rise continues, Wozniacki is stepping out of the spotlight.

The much-loved Dane announced her departure from the WTA tour last month, having realised she wanted to accomplish more in life off the court, including starting a family with husband David Lee, a former NBA All-Star.

She will end her professional career after this month’s Australian Open.

Her place at the sport’s top table is undeniable; she sits ninth on the list for most weeks (71) spent as world No.1 and claimed the 2018 Australian Open.

That tournament success is the reason why she’s chosen Melbourne Park as the site for her last event.

Before heading to Australia, she’ll play the doubles final on Sunday alongside her best friend on tour; Williams.

In Saturday’s all-American second semi, Animisova will play her idol in Williams.

“My biggest wish is to play her before she retires, so this is honestly the happiest I’ve ever been,” Anisimova said after her quarter-final win over Eugenie Bouchard.

“She’s my idol. She’s everyone’s role model and I’ve had some personal moments with her.

“To get some experience playing a match against her is something I’ve been wishing my entire life.”