I think it's fair to declare the inaugural ATP World Tour Finals at London's O2 Arena a success. And as the countdown to next year's tournament begins, I've taken a look back to see what was learned at the former Millennium Dome.

1. A change is gonna come

The Sam Cooke classic may not have been one of the tunes blasting out over the O2's sound system over the past week, but the action on the court showed that the men's game is about to be shaken up. Rafael Nadal looked a shadow of the player who was the world's best at the start of the season, while Roger Federer again came up short, losing for the first time in 13 meetings to Nikolay Davydenko. That stat says a lot and helps show that the dominance the Swiss once had is now gone. Yes, it should be pointed out that Federer again ends the year as world number one - becoming only the second player in history to regain the year-end top spot - but the Swiss used to dominate his foes in a way that showed everyone who was the ATP's top dog. That's no longer the case and even Federer's greatest fans must surely admit the pack is closing in. Nadal remains his closest challenger in terms of the rankings but his travails since his mid-season knee problems must be a major concern. Instead the leader of the pack seems, right now, to be Juan Martin Del Potro, whose forehand must now be considered the biggest weapon in the game. Hit so hard, so flat, the shot was largely responsible for his US Open triumph, while, despite minimal preparation for London, it so nearly saw him claim the end-of-season finale too. A man for all surfaces, 'Delpo' looks destined for the very top - possibly even inside the next 12 months. Federer and Nadal are not the type to go down without a fight though, while Andy Murray - rather unlucky not to reach the semis here - will hope to have a bigger say than he did this season. Even at the age of 28, the London winner Nikolay Davydenko could have an influence next term if he continues to play the sparkling tennis he did this week. All in all, the men's game is in rude health and 2010 promises to be another great season.

2. The format is right

Anyone who read my recent column on the season-ending WTA event in Doha will not have been surprised that controversy reigned when Group A reached a conclusion in London. However, people should not read into this that the round-robin format is wrong. Look at the bigger picture. The group system means the best players play each other throughout the week (each guaranteed a minimum of three matches) and that quality shone through at the O2. Very few matches disappointed and the standard of tennis was high - just what the fans wanted. Had a knockout format existed, neither of the eventual finalists would have got anywhere near the trophy. Three players in Group A may have ended on two wins and needed 'percentage of games won' to split them, but as Andy Murray pointed out "the people that go through are the ones that deserve to". If the player eliminated thinks this, it's hardly injustice we are talking about. The rules - all really rather simple once you've read them - do not need to change. What does is the communication of them to fans and players by both the tournament organisers and the media. As the BBC's radio commentator Jonathan Overend rightly said, it was an "absolute disgrace" that Del Potro had to wait on court 15 minutes before finding out he had qualified. Sadly that was a bit rich from the 5Live commentary team whose Twitter 'tweets' had been handing out wrong information to followers throughout the final set of Del Potro's match. What should happen is the display of possible outcomes on the big screen so that both players and fans know what needs to be done. It could be argued this being a distraction to the players but given Del Potro had no idea if he was through or not, surely my suggestion is better. Looking at another sport, golfers have leaderboards in their face during a round - they can simply choose not to look at them if they don't want to be 'distracted'. In short, keep the format, improve the communication.

3. The schedule needs looking at

There was criticism that the evening singles matches were starting too late and with some justification - the first point was being played around 9pm each night. That meant a lengthy three-set match could easily finish after midnight. In the end, that didn't happen but still some fans had to leave early, often with work to go to the next day. While part of the problem can be put down to London's transport system - the last tube back to central London being an embarrassingly early 12.16am - an earlier start should be possible. As is normal at most tournaments, the singles could follow straight after the conclusion of the doubles, for example. One suspects TV companies wouldn't want this, so a 6pm or 6.30pm session start could also be considered. This would push forward the 'afternoon' session start time but that should not matter. Players are regularly playing at 10 or 11am during the season. Sensibly, organisers have promised to review every aspect of the tournament, saying "that will include the schedule and the timing. If we can bring it forward, we will". That news is welcomed.

4. Doubles is back

While the scheduling will be looked at, what surely won't change is the decision to play one doubles and one singles per session. When this event was previously held in Shanghai, the doubles tournament was essentially a separate entity, being played in front of low crowds in the afternoon before the singles stars took to the court in evening. Here the doubles contests were regularly being played in front of crowds of 10,000-plus - almost unheard of on the tour. Those fans certainly seemed to enjoy it, not to mention the players, with Mike Bryan saying after lifting the trophy that he and twin brother Bob had enjoyed "the best week of our lives". With few of the singles stars playing doubles regularly these days - and even less playing the format at the Grand Slams - doubles has been in danger of dying a slow death. The attempt to raise its profile in London has worked and looks to be exactly the kind of shot in the arm it needs.

5. The O2 Arena is a great venue

If you didn't get to visit this year's tournament, pencil it in your diary for next year. You will all have seen the iconic building that was once the Millennium Dome, but the inside is just as spectacular. The cavernous main arena is ideal for tennis. It steep sides draw comparisons with Arthur Ashe Stadium at Flushing Meadows - the world's biggest tennis arena and one of very few with a higher capacity - but the indoor nature of the event adds atmosphere which can sometimes be lost in New York. With its flashing lights and big screens, significantly the O2 Arena also offers something different to what most British fans know as tennis, ie Wimbledon. While there were some empty seats at times, there's no doubt attendances were very impressive and will surely grow even more next year. How the WTA - whose Doha event has drawn small crowds in each of the past two years - must have looked on in envy.

Do you agree or disagree with Andy? Or do you have any other points to make about the action in London? Let us know by emailing tennisfeedback@sportinglife.com and we will publish a selection of the comments.