to convert two breakpoints at 4-3 15-40 as she hit two groundstrokes long before Serena held serve with two aces in a row to reach 4-4.
A large majority of points three strokes or less dominated the first set as the sisters reached the tiebreaker.
Serena for the day would prove to be the more consistent of the two past Wimbledon champions as a number of groundstroke errors from Venus and several Serena groundstroke winners set up setpoints for Serena at 6-2 in the tiebreaker.
A Serena topspin backhand lob winner sealed the first set in her favor.
In set two, Venus missed an increasing number of first serves and doublefaulted on the first breakpoint against her serve of the match to fall behind 2-4.
And with Serena hitting aces seemingly at will, the match looked to be close to over as Venus possibly was hindered by a heavily strapped knee.
Serving in the final game of the match, Venus saved three matchpoints before netting her signature shot, the backhand down the line on matchpoint number four.
By defeating the five time Wimbledon champion Venus, Serena earned her third singles title hours before pairing with Venus to take the ladies' doubles championship.
America gets the chance to celebrate a second Wimbledon singles' champion tomorrow as Roddick meets the five time champion Roger Federer of Switzerland in the men's final.
Andy Roddick (USA) v. Roger Federer (SUI)
Friday Roddick surprised a lot of people with his 6-4, 4-6, 7-6(9-7), 7-6(7-5) semifinal win versus the third seeded Andy Murray of Scotland and Britain. The American mixed in a winning dropshot with his aggressive baseline game and overpowering serve for the upset.
However Federer leads Roddick head to head 18-2 and the only major advantage Roddick has is serve speed.
Roddick, the fastest server ever in tennis, should look to hold serve easily then pressure Federer's serve. But normally in a Federer match, the opposite happens.
Winner: Roger Federer