Serena Williams triumphed once again over sister Venus to win her third Grand Slam of the season at the US Open.

The 6-4 6-3 win capped a memorable year for Serena, the world number one, who was only denied the Grand Slam of all four majors by an injury which forced her to miss the Australian Open at the start of the year.

Serena emphasised her dominance in the sport by pounding her sister's weaker second serve at every opportunity.

Defending champion Venus did not help herself, serving ten double faults in all.

The pair had already contested the French Open and Wimbledon finals this year, with younger sister Serena victorious in both.

The match got off to a great start with virtually everything happening in the very first game - an ace, two double faults, brutal groundstrokes and deft touch.

Serena immediately found great returning depth to move to 0-40 on Venus' serve, but aided by a soft-hands volley, Venus took it to deuce.

A second double fault gave Serena a fourth break chance but Venus stayed calm to hold in what had been a breathtaking opening game.

But those double faults had begun and two more in the seventh game put her in big trouble at 15-40 and although she saved one break point, Serena finally secured the first break at the ninth attempt with an off-forehand winner.

Venus immediately retrieved the break as Serena came up with some errors in game eight.

But another double fault got Venus back in trouble on her own serve in the following game and a wild forehand on break point left Serena serving for the first set.

She did so comfortably, serving out to love and clinching the set 6-4 with an ace.

Service had been the key to that first set, Serena able to hold quite easily despite having her first serve percentage below 50 per cent.

On the other hand, Serena got stuck into Venus' second delivery.

Although Venus had manged to compete during the long rallies in the first set, Serena was on top as the second set began.

Three double faults from Venus in the third game of the second set gifted a break to her sister and Serena was left in firm command of the match.

A second break put Serena within touching distance of her second US crown - she also won here in 1999 - and although Venus got one break back, Serena fittingly secured victory on Venus' serve.

Venus saved two match points but dumped the ball into the net on the third to give Serena revenge for her defeat in last year's final.

With three straight wins in Slams against her sister, you could say that revenge has been well and truly exacted.