"Venus Williams' return to tennis is even more impressive than I'd realised."

If there’s ever been a year that’s all about Serena Williams, it’ll surely be 2017. Last night, Serena took out the Australian Open in straight sets, her 23rd Grand Slam title and another win over her equally famous older sister.

But what 2017 should also be known for — perhaps even more importantly — is Venus Williams and her triumphant return to tennis.

To me, Venus has always been Serena’s older sister. An incredibly talented and an impressive sports player in her own right, but the older sister of the “real” talent, nonetheless.

After all, it’s not like Venus ever went away, exactly — it’s just that Serena’s star began to shine more brightly. (For the record, it’s not like I’m not deeply embarrassed about seeing her this way or my naivety, but it’s also not an uncommon view.)

Within minutes of seeing Venus play at the Australian Open against Anastasia Pavlyuchenkova on Tuesday last week, I was reminded of her power and ability, and the many, many accolades the 36-year-old's career boasts.

The five wins at Wimbledon, the two wins at the US Open, the four Olympic gold medals.

I was also was reminded of something I had read in passing years ago but promptly forgot; Venus Williams suffers from the rare autoimmune disease called Sjögren's syndrome.

Both incurable and without a clear treatment method, Sjögren's syndrome affects the moisture-producing glands of the body. Its side effects include things like dry skin, a dry mouth, dry eyes and chronic coughing, as well as more severe symptoms like numbness in the arms and legs, joint and muscle pain, extreme lethargy, and thyroid problems.

For anyone, being diagnosed with the disease would be heartbreaking. But it's hard to imagine just what that would mean for an elite athlete in the prime of their career as Venus was when she was diagnosed in 2011.

Despite learning of her illness six years ago, like many illnesses, it's not like the signs and symptoms came on suddenly. In the years prior to her diagnosis, Venus said she would often wake up without energy; lethargic and struggling to kick the covers off and get out of bed.

"I think overall, it was sad for us but at the same time we were happy that we knew what was wrong," Serena told CNN following the news.

"It has been a challenge, and a challenge to myself, and really just knowing that I can't be defeated by anything," Venus conceded in the same interview. "I've lost and I've had to learn -  but I've never had to lay down the towel, so to speak. "

On Tuesday last week, though, Venus took to the court at Rod Laver Arena and battled hard to claim victory throughout the first set. In many games, it seemed like she might not win. She was visibly frustrated and struggling, walking away from the court head down and stretching her shoulders out between serves, but also clearly determined.

By the second set, she showed a steely stubbornness and fought with strength drawn from the bottom of her tank. Incredibly, it led to her taking the set and the match. And within seconds of winning, Venus had wrapped her arms around herself and spun around in the joy of the incredible achievement her body had just accomplished.

Anyone watching the match could see that Venus Williams is a player truly in love with and thankful to be in the game of tennis. No tantrums, no dull post-game interviews, no comments about poor performances from other players, but rather someone whose biggest hurdle to achieving their goal is their own body.

And really, in this day and age of tennis, how often do you see the world's best players unashamedly and ecstatically happy to be on the court in a near two-hour battle in the summer heat?

"It's wonderful to be here at the start of the year," Williams said euphorically following the match.

"I want to go further, I'm not happy with this," she said.

Incredibly, Williams' win on Tuesday was yet another history-making moment. At 36, she was the oldest woman to reach the semi-final of a Grand Slam tournament in 13 years.

When explaining how her condition affects her training, Williams said, "my motto now is that is all adds up, so if I can only do a little bit this day, it will add up, and it's better than if I get discouraged and don't do anything. That's when I really start sliding downhill.

The fact Venus did not win the Open last night was kind of irrelevant. Because it still feels like she's won.