As their careers go on and on and on, and their legacies continue to grow, I become more and more convinced that we, as sports fans and mere mortals, simply aren't worthy of the greatness of the Williams sisters.

On Monday, Serena and Venus Williams faced off for the 26th time at the pro level. This time, it wasn't in a final or even a semi, but rather the fourth round of Wimbledon.

There was some suspense leading into the match -- Venus (ranked No. 16) looked better than top-ranked Serena did during the first week of the tournament, and Venus actually defeated her younger sister the last time they played each other in the 2014 Rogers Cup -- but Monday's match went pretty much according to plan, with Serena winning 6-4, 6-3.

The 20-time major champion was dialed in, and although Venus didn't play poorly, she couldn't keep up with her sister on this day. Serena didn't celebrate much after the match, immediately taking to social media to honor Venus.

Unfortunately, the fanfare that surrounded the encounter died off rather quickly, like it was just like any other fourth-round routine win. But Serena put things back into perspective.

"I just thought, 'Wow, I'm 33, and she just turned 35. I don't know how many more moments like this we'll have.' I plan on playing for years, but you never know if we'll have the opportunity to face each other," Serena said, as reported by the Associated Press. "I just took the moment in, and I thought, 'We're at Wimbledon.' I remember when I was 8 years old, we dreamed of this moment, and it was kind of surreal."

Serena's right -- it is absolutely, positively surreal that Serena and Venus are still playing each other on the biggest stages of tennis in their mid 30s. Just as it's surreal that two sisters from Compton without a family tennis pedigree would face off even once as pros, let alone 26 times.

It's surreal that together, Serena and Venus have absolutely owned Wimbledon, the most conservative of all the Slams. In 10 of the last 15 years, a Williams sister has hoisted the Venus Rosewater dish. The siblings have met six times on the lawns of London, including four finals and a semifinal. They each have five singles titles at the All England Club, and together they've won the doubles crown five additional times.

It's despicable that pundits, including Jason Whitlock, still have the gall to use their platforms to accuse the Williams sisters of disrespecting the sport. In the lead-up to their Monday match, Whitlock -- who has baselessly attacked the sisters, especially Serena, throughout their careers -- went on national television and claimed that Richard Williams would pick the winner of the match, an accusation that was rampant when the sisters began playing on the WTA, but died out over a decade ago.

It's beyond ridiculous that we're still at a place where matches between the Williams sisters are viewed with anything other than utter astonishment.

Serena and Venus are two of the best athletes in the history of tennis, and two of the most decorated and inspirational athletes in America, from any sport and either gender.

Venus has won seven major titles and 46 career titles in singles alone. She has been No. 1 in the world, defeated Serena more times than any other player has (11), and fought for and -- and earned -- equal prize money for women at Wimbledon. Recently, she has revitalized her career in its twilight despite the energy-sapping autoimmune disorder Sjogren's Syndrome.

She's not on her sister's level anymore, and isn't a GOAT candidate, but Venus is still the second-best American female tennis player in the world, a steady top-20 presence, and has been in five finals over the past 18 months, winning two of them. She is currently the oldest player in the top 100. She is a legend.

Serena, of course, is in a league of her own. She is chasing another Serena Slam here at Wimbledon, the second time in her career that she's been the reigning title-holder of all four Slams. If she does achieve that, it would bring her Slam tally to 21, and keep her hopes for a Steffi Graf-tying 22 and a Calendar Slam alive at the U.S. Open.

While she's younger than Venus, Serena is no spring chicken -- she's the fourth-oldest player in the top 100, and the oldest player in the top 10 by five-and-a-half years.

So it doesn't really matter if it's awkward to see two sisters face off, or if the tension in their matches doesn't always produce the best tennis. It doesn't matter if the matches are over in straight sets or if the expected player wins.

There should be a national celebration every time Serena and Venus play each other. We're already seeing in tennis how hard it is to produce American tennis stars -- the last American woman to win a Slam that wasn't a Williams sister was Jennifer Capriati back in 2002. The odds of producing two American stars capable of both winning multiple Slams and holding the No. 1 ranking and are in the same generation are slim. The odds of both of those players coming from the same family once again? Forget about it.

Serena and Venus have spoiled us with their greatness, and though we're lucky that they're both still enjoying their time on the courts, they won't be around forever.

We need to appreciate what we have before its gone.