Betting on tennis has changed markedly in recent years. Once upon a time, bookies would offer a selection of matches, then close all markets when the match was scheduled to begin. Now in the technological age, we have live scoring from most tournaments, live television coverage and in-play betting.

For punters, this means it's a whole new ball game.... To my mind, the best thing about betting on tennis is the live action. A two-runner market which can vary markedly on a single line call or unforced error offers enormous opportunities for the sharp-minded punter. But more about that later.

Outright betting The French Open and Wimbledon are the two Slams with the least number of genuine winning chances. This is due to the specialist nature of the respective playing surfaces. Hardcourt is more of a 'middle-ground' surface which gives a greater number of players some chance. Backing favourites in Slams has never been my go - the outright price at any time is always shorter than the combined all-up price, and that's without factoring in the fluctuations in-play. Even a brilliant player like Federer will have the odd shaky set where his match price drifts above the pre-match odds. Let's take a look at clay - it is a different matter entirely to other surfaces.

(This next section was written before the French Open 2005).

If you pull apart the Federer Express' clay record, I'd be inclined to lay him. So he won in Hamburg in the leadup event, he's in great form. Well, actually, he won there in 2002 and 2004. His record at Roland Garros those years - R1 loss to Hichan Arazi, and R3 loss to Gustavo Kuerten. He has won two matches on the Paris dirt in his last three visits. Would you want to back him at 3.5?? In Grand Slams, the outright markets always have good depth. My personal preference is to look for longshots to trade on in the hope they can make it through a couple of rounds and the seeds start to fall away. If you can find a decent claycourter drawn amongst seeded players better known on other surfaces, you've found a prime candidate. How high a price you go depends upon how much you are looking to risk or win. If you're happy locking in a profit of a tenner, then aim high - 600+. If you're chasing three- or four-figure profits, then you might be better off looking at players in the 50-100 bracket.

Points to take note of when trading outright markets:

1. Liquidity and market percentages are stronger overnight, many layers play safe and cancel their offers when play begins. If you want to leave yours up whilst play is going on, work to wider margins (ask for a few points higher to back, and lower to lay) as you can't focus on all the courts at once.

2. Many punters over-react while a match is in progress and will take a lower price than what will probably be available after the match when the dust has settled. Think about what price you would take after this match - ask for several points lower if you are keen to lay, or several points higher if wanting to back your player.

3. Not everyone will be watching the same match as you in the early rounds. With the advent of digital TV, international broadcasting and live online scoring, punter interest could be spread across any of a dozen matches at a time.

4. If a seeded player is in trouble, instead of focussing on laying the player in question which many punters will be doing, look at the players around him in the draw. Suddenly that price of 40 on the guy he was drawn to meet two rounds later appears great value as that price might be halved is the seed is knocked out.

Match betting

I will make the bold assumption here that you have a basic understanding of form and the relevant statistics for the sport. If not, your task becomes a little harder, but the Betfair market, being at near enough to 100% most of the time, provides a very accurate guide to the combatant's chances. The beauty of betting in-play comes when you see how punters can over-react to certain points in a match. The value of a break point for instance depends upon what stage of the set it is (eg, at 4-4 it is far more crucial than at 2-2), the strength of the server (Andy Roddick currently leads the break points saved category for 2005, at 73%), the quality of the receiver (Xavier Malisse leads the break points converted category at 54%) and the likelihood of the receiver then being able to hold serve in reply. You'll often hear commentators say it's not really a break until you've held your own to take full advantage.

On clay, the value of a break is significantly less than faster surfaces. Look at the most service games won stats - top five of Roddick, Federer, Arthurs, Karlovic, J.Johansson - compared to the most return games won - Nadal, Coria, Ferrer, Nalbandian, Gaudio. The servers love the faster courts, but the claycourters are the ones who break serve more often, yet also are prone to losing their own service games.

My point is, an early break in a match doesn't necessitate a huge collapse in price. Nor for that matter does a one-set lead over the best-of-five sets. Breaks of serve come far easier on clay so holding a lead is considerably more difficult, whereas the reverse effect happens on grass. At the end of a set, the mindset of a player can change significantly. The player who won the last set may take his foot off the accelerator and relax a little, or the player who is down might suddenly come out with all guns blazing, knowing he has to strike back quickly to stay in the contest. How fine was the line between winning and losing that previous set? If it only came down to one key point or double fault, then you should be looking at laying the leader as the price is likely poor value.

Sometimes you will see a guy simply playing 'out of his skin', landing every first serve, hitting winners left, right and centre etc. It is very rare for a player to sustain that sort of pace for a whole match in a Grand Slam, unless they one of the event favourites. That's a prime time to lay.

Remember when you are betting in-play, you are not necessarily focussing on the end result. You are concentrating on the fluctuations of the match, trying to lay low and back high. Backing one player is the same as laying the other, so make sure you understand reciprocal prices (laying 1.50 = backing the other player at 3.0). If you struggle with converting decimal odds in that fashion, think in fractions (lay 1/2 = back at 2/1).

More often than not, most of the volume is traded on the favourite, but in a swinging match, that player might vary, so you may need to trade on both sides rather than just one (as you might do on a horse race or soccer match).