Sport's most enduring sibling rivalry will be played out on US Independence Day after Venus Williams exacted brutal revenge and Serena Williams displayed raw desire to inflict a double defeat on Russia at Wimbledon. The American sisters will be setting off fireworks on women's final day for the second year running at the All England Club, but on Thursday Serena came within a heartbeat of missing out on the Fourth of July celebrations. At 4-5, 30-40 down in the deciding set, Serena was staring defeat head on as Elena Dementieva stood one point away from reaching her first Wimbledon final. Instead, a split second's hesitation by the Russian allowed Serena to hit a wobbly backhand volley off the tape and the American snatched her get-out-of-jail free card to crawl over the finishing line with a 6-7, 7-5, 8-6 win over the fourth seed. Clocking in at two hours and 50 minutes it was the longest women's semifinal match at Wimbledon since records started being kept in 1969. “It's definitely one of my more dramatic victories. I felt like I was down pretty much the whole match. To come out on top was, you know, a great feeling. I wanted to win really bad,” Serena told reporters. While little sister Serena had to fight tooth-and-nail to survive a match that showed off everything that is good about women's tennis, Venus proved that there is still a gulf between her and the rest of the women's field at Wimbledon when she walloped clueless top seed Dinara Safina 6-1, 6-0. Safina's ranking as world number one looked like a statistical error as she suffered the ignominy of suffering the most lopsided semifinal defeat since Billie Jean King beat Rosie Casals by the same score 40 years ago. The Russian sprayed errors long and wide to fold in just 51 minutes. Grilled about whether she deserves the top ranking after her outing, Safina could only say: “It's definitely disappointing, finishing the match less than one hour and winning only one game ... I have to swallow this defeat but it's not the end of the world.” A backhand service return into the net not only ended Safina's ordeal but also handed Venus her 35th consecutive set at Wimbledon as she set up the dream final everyone had expected long before a ball had been hit at this year's championships. Venus, who was beaten by Safina when they met in the Italian Open semifinals just two months ago, was delighted that the sisters were back where they belonged. “I'm happy for Serena to be in the final but I have to face her and defeat her. I don't necessarily want her to lose, but for sure I want me to win,” said Venus, chasing a hat trick of Wimbledon singles titles, and her sixth overall. “I don't like to ever see her disappointed in any way. But at the same time, I don't want to see myself disappointed. “But if she didn't win (her semifinal) or if I didn't win then the dream doesn't come true that we're both playing in the final. So I definitely want to play against her, because the dream has come true for both of us and for our family, too.” While Venus kept that dream alive by stroking winners with the relaxed air of a woman on a sun-lounger sipping a Pina Colada, Serena could not believe what had hit her. In a match featuring sinew-stretching rallies, crafty angles and thundering serves, Dementieva completely neutralized Serena's power game to take the first set. But Serena broke the spell to gallivant into a 3-1 lead only to see the Russian defy logic and come back stronger and harder at her. Since the American's forehand “didn't show up today and went on vacation to Hawaii” she turned to her B-plan, to try and play round her erring stroke. Just when it seemed as the second set would head into a tiebreak, Serena struck lucky with two identical netcords – with Dementieva's forehands bouncing off the tape and wide – to break for a 6-5 lead. The Russian had four chances to break back in the next game but was undone by two venomous Serena aces and two errant shots from her own racket, much to the dismay of the shrieking Dementieva who crouched down behind the baseline and covered her face in disbelief. Still the Russian would not give up but could do little when her 3-1 lead in the third set disappeared in a blink of the eye as Serena roared herself on to stay in the match. At 3.40 P.M. local time, Dementieva looked to have one foot in the final but then her head started to spin and 23 minutes later Serena had completed one of her greatest ever escape acts. “I wasn't sure if it's Serena or Andy Roddick on the other side of the net, 125mph all the time,” the 27-year-old Dementieva said summing up her experience of facing 20 aces during the match. The demise of Russians ensured the most famous family in women's tennis will come out for a fourth Williams final in south-west London and with the sisters locked at 10-10 in their head-to-heads, it promises to be an intriguing affair.