Serena Williams vs Victoria Azarenka playing a Grand Slam semi-final should not, in an ideal world, surprise most tennis fans. The former world No 1 players have played 10 times at the level before across the four Majors – including two terrific US Open final matches – since their first meeting at the 2008 Australian Open.

But what should surprise tennis watchers is the circumstances ahead of their 11th Major meeting – at the 2020 US Open, being played without fans after a six-month shutdown of the sport.

In a Grand Slam where Williams is the third seed but struggling to close out matches in straight sets while Azarenka is unseeded but on a 10-match winning streak after lifting the Western & Southern Open.

At a tournament where three of the eight quarter-finalists are mothers who returned to the tour.

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In a semi-final match up that is both familiar and unexpected, tennis fans have a chance for a fascinating throwback to a different time.

In 2012 and 2013, Azarenka seemed to be the only one who could be a consistent threat to Serena Williams on the hard courts. Even though their overall head-to-head record stands at a lop-sided 18-4 in Williams’ favour, their rivalry was a fascinating one.

In both those years, Azarenka won the Australian Open (without facing the American) while she lost to Williams in hard-fought finals of the US Open. The player from Belarus beat Williams in four finals (losing five) even as the American won all 10 matches played at Grand Slams. Azarenka beat her in the finals of Miami, Doha, Cincinnati and Indian Wells – all big Premier hard-court events.

She had a striking game that could face Williams’ power game, trouble her on return while matching the groundstrokes. Five of their matches at Slams have gone the distance.

On her part, it always appeared that Williams respected Azarenka more than several other opponents and their matches were generally tough but their relationship friendly.

However, like so many other two-time Grand Slam champions in the 2010s, Azarenka was unable to maintain the consistency at Majors, even as she did well at the Premier WTA tournaments.

But unlike the other winners, Azarenka didn’t just fade away, but rather had to take an extended break away from tennis, first to give birth to her son Leo in 2016 and then because of a long-standing custody battle with the father.

As a result, when she returned to the tour in 2017 her ranking and then performance dipped. She spent the past four years ranked outside the top 50 and tough first-round draws didn’t help. Despite having most of her weapons intact, she just couldn’t get to the level she needed to win and most thought she was past her prime, with retirement talk swirling at 31.

In contrast, when Serena Williams went on maternity leave, her last tournament was an Australian Open victory while pregnant and even after a return as an unranked player, she climbed up the charts quick with Wimbledon and US Open runner-up finishes in 2018 and 2019. The 38-year-old may not have won that elusive Major since but she continued making deep runs at big events and building up points.

The contrasting journeys mean the two will clash as the third seed and an unseeded semi-finalist, even as the Belarusian has risen to world No 27 after her title last week by walkover against Naomi Osaka. The relocated Cincinnati event was her first title as a mother and it has proved to be the turning point her game was waiting for.

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Incidentally in her final two titles before becoming a mother, Azarenka had beaten Williams in straight sets to win Indian Wells and then completed the Sunshine Double at Miami in 2016. Those hard-court wins were to mark her resurgence after a middling 2014 and 2015 season but the year changed the direction of her career.

Now, more than four years later, it seems Azarenka has found what she was looking for with her first Grand Slam semi-final since 2013. But standing in the way of her first final in seven years is someone she is yet to beat at a Major.

The 31-year-old said she is excited to player old friend again. As she should be, given this looks like her best shot at finally beating the American at a Grand Slam.

Williams has had to dig deep to carve out wins in the last few weeks with eight of her 10 singles matches since the last month’s restart going to three sets, including the last three at the US Open against Sloane Stephens, Maria Sakkari and Tsvetsana Pironkova.

On the other hand, Azarenka has dropped just one set so far, knocking out 20th seed Karolina Muchova and fifth-seeded compatriot Aryna Sabalenka. In her quarter-final, she was clinical dropping only ONE game against 16th seed Elise Mertens.

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With the quarterfinal and semifinal on consecutive days, the match will be an added physical challenge for Williams who admitted feeling tired in the last match. She has willed and served herself out of trouble so far, holding a mental edge if not a physical one in her matches.

But Azarenka comes in with a trait none of her previous opponents had – the confidence that she can beat Serena at her best. With her precise, paint-the-lines hitting and improved fitness as well as the experience of having been here before, she will believe she has the edge.

No matter which way this semi-final goes, tennis fans can be assured of a fascinating encounter – a match-up both vintage and exciting.