ATHLETICS:ACCORDING TO Sun Tzu, the Chinese political consultant of the fifth century BC, the first lesson of his masterpiece The Art of War - "Know your enemy" - is the most important. It's also the first lesson for any athlete competing in Beijing's Bird's Nest over the next nine days.

They'll have spent the past several days scrutinising the enemy. There is no more forlorn excuse in the Olympics than to say you underestimated the opposition.

For Robert Heffernan, knowing the enemy is easy, given he trains with many of them and has the same coach as the gold-medal favourite. Early tomorrow he'll leave the Bird's Nest at the start of the 20-kilometre walk, and after five circuits around the Olympic Green, will return eighty-odd minutes later, at which point the medals will be decided.

It's difficult to say whether Heffernan is capable of getting among them. To begin with, the 20-kilometre walk is notoriously difficult to predict. But he was sixth in the World Championships in Osaka last summer. His Irish record of 1:19:22, set this summer, ranks him eighth-fastest in the field of 53 entries. In terms of experience he rivals any of them.

Eight years ago he competed in Sydney as a starry-eyed 22-year-old and finished a creditable 28th. Four years ago he competed in Athens thinking he was a stronger and wiser walker, and was disqualified.

After that, and a succession of injuries, he was in danger of drifting from the event, until two years ago Robert Korzeniowski from Poland agreed to coach him.

Korzeniowski is widely considered the greatest walk walker of all time - having won four Olympic titles, including the 20km and 50km in Sydney, and the 50km in Athens, after which he retired.

"The training, back then, was so up and down," says Heffernan. "We were hitting our peaks at all the wrong time. It was ridiculous. We'd come back after a world championships and go straight back into hard training. We'd be flying in February and wrecked by August.

"With Robert, the recovery is always important. We took the whole month of November off. Just progressing then after that, getting more and more specific the whole time. It's all very professional with Robert. He uses me as an example of someone coming from the wrong walking background, if you know what I mean. I get chastised because he's done it all. I'm the only one that has never won any medals."

Heffernan, in other words, is coming to his peak. At 30 he's far from old for an event where age mostly means familiarity. The problem is that so many of his enemies are peaking too - including Spain's gold-medal favourite, Francisco "Paco" Fernandez, the one also coached by Korzeniowski.

Walking is an esoteric pursuit and so walkers are a tight bunch. There is limited competition and they usually share training camps. Heffernan will be on first-name terms with practically all 52 opponents tomorrow morning.

"There is good camaraderie, but it is very competitive at the same time. We were on the track one day recently in Font Romeau, I was taking my lactic measure afterwards, and all the Polish lads were looking at me - laughing, because they were so high. 'Do you want to race?' you're thinking, on the tip of your tongue.

"The funny thing is everybody wants to be the man. But I've been down this road before. You know what to expect, the hype, all of that. You just have to zone out from that. I just see it as another race, in China."

This evening he'll sit down with Korzeniowski to talk strategy. One thing they won't be discussing is the need to watch his warnings: "It's funny, because I'm still asked the question, 'do you ever get the urge to run?' It's just so totally different with race walking. It's like asking someone who runs the 5,000 metres on the track do they ever get the urge to stop and walk. They know straightaway if they do that they'll finish last.

"It's all about being strong enough, mentally and physically, to hold your technique together. I remember in Osaka last year, Robert gave me a plan, to stay back. I remember saying I didn't want to stay back. The thing is instinct will nearly always take over anyway."

Alistair Cragg, meanwhile, gets the honour of being the first Irish athlete in action this evening, his 1,500-metre heat set for 7.20pm (12.20pm Irish time) at the Bird's Nest. The field includes the reigning world champion Bernard Lagat, runner-up for Kenya in Athens 2004 but now running for the US.

The only other Irish interest on the opening day is in the heats of the women's 3,000m steeplechase (from 1.25pm Irish time). The event was part of the past two world championships, makes its Olympic debut in Beijing and has 17 runners in each of the three heats.

Fionnuala Britton faces a difficult task getting out of heat one, with Russia's world-record holder Gulnara Samitova one of 12 starters with faster times this season. Róisín McGettigan goes in the second heat having run a season's best of 9:30.56 just over two weeks ago, and in that form can be confident of progressing.