The old boxing cliche has it that a big good 'un will always beat a good little 'un; and in boxing there are different weight divisions supposedly preventing serious mismatches.
The physical miss-match on Centre Court on Saturday afternoon pitted a 155lbs middleweight against a 125lb featherweight and for 40 minutes the outcome looked sadly predictable: feathers tend to be blown away and that seemed likely to be the fate of Poland's Agnieszka Radwanska.
In that first set it was. Statisticians were checking back for the most one-sided women's final of modern times (Billie-Jean King's 6-0, 6-1 against Evonne Goolagong in 1975); and the crowd, who had paid £105 apiece, were reduced to grateful applause for every Polish point amid the fear of witnessing a humiliation. Thankfully they received better value from then on as Radwanska came out defiantly after a rain break for the second set and even managed to draw level. OPT: Perhaps Serena, subconsciously or not, was saving something for the doubles final with her sister.
Of course in there has always been a chance that a Radwanska or a Justine Henin - now sadly retired - could overcome one of the big girls with touch and grace. Yet it is fair to say that the face of women's tennis changed when the Williams sisters emerged towards the end of the 90s. Venus came from nowhere to finish as runner-up at the US Open of 1997, aged 17 and two years later her younger sister won it at the same age.
Between them, they now have the little matter of 21 Grand Slam victories. They have recorded the two fastest serves ever by women: Venus's 129mph, Serena's 128.
In the semi-final victory over Victoria Azarenkia last Thursday, Serena achieved a new world record with her 24 aces, beating her own previous best. Yesterday one of the 17 that fizzed past Radwanska beat her own record for a single tournament of 89, which was extended to 102. She reached three figures by taking one game with four in succession. In the end, this was ultimately another power-point presentation.