American court queens Serena and Venus Williams have been hailed the super "freaks" of Wimbledon as they bid to set up a fifth final showdown.
The irrepressible sisters will play for the Venus Rosewater Dish at the weekend if Serena sees off surprise semi-finalist Elena Vesnina on Thursday and Venus overcomes Australian Open champion Angelique Kerber.
Following past meetings in the 2002, 2003, 2008 and 2009 finals, it would be an improbable reunion at the peak of the women's game for the US superstars, after Venus looked to have lost her once formidable aura on the grand slam stage.
Serena turns 35 in September and Venus is already 36, with both having made their Wimbledon debuts as teenagers in the late 1990s, and they appear as agile and hungry for success as ever.
Their spectacular achievements remind the 1999 Wimbledon champion Lindsay Davenport of Martina Navratilova's success in her mid-thirties.
"It really goes to show the athleticism that Venus and Serena have," said American Davenport.
"Obviously when they first came up we could see it and you can talk about it but what they're doing is really, really hard.
"What Martina Navratilova did, they are in the most complimentary way such freaks because their athleticism is so great.
"To be able to compete at that level at that age is remarkable. You almost forget, Serena's almost 35. It's a tough sport, it's hard to really get out of bed some mornings, and they make it look so seamless. It's amazing."
World number 50 Vesnina, who was ranked as low as 122nd in February, may find herself out of her depth against Serena Williams, but Kerber starts as favourite against Venus, who contests her first Wimbledon semi-final in seven years.
Being written off repeatedly has only galvanised Venus, who suffers from the fatigue-inducing condition Sjogren's syndrome. According to Davenport, 40, the five-time Wimbledon champion deserves every plaudit for this year's run.
"People have kept asking, 'When are you going to quit, when is the end?'. The fans want to know, the media wants to know, and she has been steadfast that she doesn't want to quit," said Davenport, who lost to Venus in the 2005 Wimbledon final.
"People have questions about players - are they mentally and physically strong enough to last through a tournament? Can they muster the magic again? And she's just always believed in herself. It's been amazing to watch her play here.
"To be 36 and also carry an auto-immune disorder, I can't even comprehend how tough that is day in and day out. You hear about the joints and all the pain that brings. You run out of superlatives for describing her and her whole road and journey."
The sisters will be sorely missed when they retire, former US Open champion Tracy Austin said.
Austin became a grand slam winner at the age of 16 in 1979 but injuries cut her off in her prime, and she is staggered the Williams sisters have remained at the top of women's tennis for almost two decades.
"We've become accustomed to them being there just about every single year, and I think that when they do leave there will be a big hole," Austin told Press Association Sport.
"We will miss them because they have huge personalities, a lot of charisma, their style. They changed the game, being the first two who came through who could hit offensively from a defensive position.
"They changed the way people played. It made everyone need to go back into the gym and get stronger themselves. They've changed the physicality of the game."
Should Serena lift her seventh Wimbledon title this Saturday, as Austin is convinced she will, then she would match Steffi Graf's open era record of 22 grand slams.
Navratilova's record Wimbledon haul of nine titles would also come into sight.
"Let's just try for seven," Austin said. "There's a lot on the line here trying to tie Steffi. She hasn't won a grand slam since Wimbledon last year.
"That's still not that long ago and most people would be happy with that. But when she won her 21st last year we thought that by the time Wimbledon came around again she would have won 22 already. I think she's going to get number 22 here."
Source: PA
