Serena Williams has had a remarkable turnaround since her 2014 Wimbledon appearance. And it's possible no one will care if she reaches the semifinal round at the Australian Open.

Serena and sister Venus matches, they will meet in a Grand Slam event for the first time since the Wimbledon final.

In 2009.

Venus Williams a threat to sister Serena at the Australian Open?

All eyes likely will be on older sister Venus, whose tennis career has been sidetracked by health issues.

In 2011, she revealed that she was suffering from Sjogren's syndrome, an auto-immune disorder that saps her of her energy. Williams has not advanced to the quarterfinals in a major since she reached the semis of the 2010 U.S. Open, ESPNW reported.

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Last year, she said revealed that she had switched to a vegan diet, which helped her combat her illness, and she won a tournament in Dubai in February of 2014 for her first title in two years.

This year, she is unbeaten in nine matches, having beaten Caroline Wozniacki in the finals at Auckland, an Australian Open warmup.

While media and fans are marveling at the 34-year-old's comeback, she is less impressed with the fact that her fourth-round win over No. 6 Agnieszka Radwanska 6-3, 2-6, 6-1 has been labeled her biggest win in years.

"I guess from the outside looking in, it could look like that," she said, according to ESPNW.

"But for me, I'm just really focused and poised right now. I feel like I've been here before, so it's not like I'm jumping up and down for joy, 'Oh, shoot, what is this? I've never done this!' Yes, I've done this. This is what I'm always going into each tournament thinking I want to do, even when I fall short. It's definitely not the first time.''

But it's the first time in a while, and the seven-time Grand Slam winner has had an influence on her higher-ranked, younger sister's game.

"She's a big influence, obviously," said Serena. "The way she's playing, her confidence exudes and permeates to me. It's a really good feeling."

Serena's own triumph over her mysterious Wimbledon appearance has been impressive. She appeared disoriented in a doubles match with Venus after losing in the third round of the singles play. Speculation mushroomed about her personal life as well as her game.

The younger Williams silenced her critics by winning the U.S. Open and the year-ending WTA Finals. She has 18 Grand Slam victories, and her next one will move her past Chris Evert and Martina Navratilova for sole possession of third place on the all-time Grand Slam wins list.