Williams' play seventh grand slam final

An all-Williams grand slam final looms at Wimbledon for the first time since the 2005 US Open and with it the question of how motivated and keen one sister is to beat the other.

The final on Centre Court (2300 AEST) Saturday at the All England Club has the potential to be great with both Williams sisters, holder and four times champion Venus and twice winner Serena, in excellent form.

The sisters, with seventh seed Venus, at 28 older by 15 months than the sixth-seeded Serena, say that throughout their parallel careers each has always done her utmost to outdo the other.

Serena said sibling rivalry motivated her to want everything her sister had achieved and more when she spoke after her semi-final victory over Zheng Jie of China on Thursday.

Venus was more vehement when she said after beating Russian Elena Dementieva, that she found suggestions that there might be a family agreement on the outcome of their matches offensive and an insult to her professionalism.

Dementieva was quoted as saying the outcome would be a family decision, no doubt meaning it would be settled within the family because a Williams would win come what may.

However, Dementieva said she would find it hard to play against a family member.

The sisters do not celebrate their victories over the other, particularly grand slam finals, with the euphoria players normally display at the moment of winning one of the biggest prizes in sport.

But if their rivalry is as strong as it has been over the 10 years since they first clashed at the 1998 Australian Open, a second round victory for Venus, the crowd can expect a highly competitive match.

Serena has won more grand slams, eight to Venus' six, but the older sister is going for her fifth Wimbledon title in her seventh final to Serena's third in four.

The younger sister won the finals between the two at Wimbledon with victories over Venus in 2002 and 2003, relinquishing her crown to Maria Sharapova in the 2004 final.

All told, Serena has the edge at 8-7 in all their meetings, having won five of their six grand slam finals and her greater power may be the decisive factor.

Both are serving well, particularly Serena, in games that do not differ greatly with both keen to come forward and volley whenever the opportunity presents itself.

They put their rivalry aside on Friday, though, to win a women's doubles semi-final as they seek to add to the two Wimbledon titles they won together in 2000 and 2002.