Tear up those early drafts: this version of the sister act could be the definitive classic

If Venus and Serena Williams can both bring their best tennis to centre court today the women's singles final has the potential to be an outrageously good match. If they can set aside the fact that they are sisters and have a conflict on the court, then I think everyone will appreciate more what Wimbledon is witnessing.

The Williamses haven't played good matches when they have faced each other and, if their meeting is going to become as regular an occurrence as now three of the latest four slam finals suggest, they need to produce a good spectacle soon. Yet that is so easy to say: none of us has any idea how difficult it is to execute.

The reaction to their semi-final wins was muted, partly because the matches were lacking and partly because people aren't excited about this match-up in a final. But don't get lost because there's not that natural rivalry yet. Fans have to realise it's one of the great stories in sport and appreciate what the sisters have accomplished: African-Americans from a poor background, who grew up in a tough part of Los Angeles, making it to the top of a white-dominated sport.

The pair continue to write tennis history and when they play each other you are clearly seeing the two best players in the world. Within a couple of months the gap has grown even wider between them and the rest. Not having Lindsay Davenport and Martina Hingis around has added to the divide, while Jennifer Capriati isn't quite where she was in the first part of last year and the Belgians have not made the step up yet.

From a positive standpoint the Williamses' play, physically, mentally and emotionally, is of such high quality that they have raised the bar even higher. It's like Tiger Woods in golf. People are enthralled with what he's doing and I hope the same thing happens with Venus and Serena.

Sometimes there's a double standard between men's and women's sport. In men's sport if a champion jumps ahead of the field and raises the bar higher, it's a positive. In women's tennis they look at the negatives.

The Williamses' movement and power is like nothing tennis has seen before. That doesn't mean in time someone can't match them, but it's up to the rest. The sisters are at a different level now.

I think this final is a bigger match for Venus with Serena now taking over at No1 in the world. Serena has been the first one to be able to look across the net and see her sister as an opponent. Now Venus needs to do the same thing. She needs to see her as a rival and realise that once they shake hands they can become sisters again.

Serena, based on recent play and having won their past two matches, has got an edge. It's almost like she has overcome the inferiority barrier of the younger sibling syndrome. The advantage that Venus will have is that it's her third straight final - she's done it all before and she's going for her third win in a row here.

Though we knew Serena had the potential to be No1, she hadn't shown over a sustained period of time any hint of what she's given us since last August. But with her record in the past nine months she deserves it. I talked to her in Munich after she won the Tour Championship last November and she looked at me in the eye and said: "My goal next year is to be No1 in the world."

The only setback since then was her sprained ankle in Sydney that put her out of the Australian Open. She's lost only two matches this year and four matches in 12 months. She's not only the best player in the world right now, she's also the most improved player.

Yet head to head Serena and Venus are very well balanced. Venus has a more powerful first serve, while Serena gets a higher percentage in. Serena's second serve is better and against Amélie Mauresmo in the semi-final it was one of the best shots on the court.

Serena's forehand is stronger as she creates better angles and puts better control spin on it. But Venus's backhand, volleys and instincts as to when to come to the net are superior. Venus discovered how to use the volley effectively when she won here two years ago but Serena is improving in this area.

They are equally excellent in their movement but at the back of the court Serena has a slight edge. Overall it's an incredibly close match to call if both players are at their best. It could be a classic. Let's hope the sisters can live up to the occasion.