Britain's Dean Macey produced the run of his life in Sydney to end the opening day of the decathlon just eight points off top spot.

Macey shattered his personal best in the 400 metres in the Olympic Stadium by 0.31 seconds to leap from fourth overall to second.

The 22-year-old clocked 46.41 seconds to win the final event having also set a personal best when triumphing in the long jump hours earlier.

Macey, who was second overall after the first day in Seville last year before going on to win silver at the World Championships, fell to his knees on the track after his lung-busting effort.

The former Canvey Island lifeguard will head into tomorrow's final five events with a total of 4546 points with American Chris Huffin, who has led since the opening day, on 4554.

Macey had trailed Huffin by 102 points going into the 400 metres but was almost two seconds quicker than his rival to claw back a massive amount of points.

Estonia's Erki Nool, partly coached by British decathlon legend Daley Thompson, is back in third 41 points behind Macey.

The Essex athlete, who famously said that he would like the Olympics to be staged on Canvey Island, is well placed in second spot.

Macey emerged from obscurity to win silver in last year's world championships and looks to be a major threat against one of the biggest fields ever assembled for a decathlon event.

Daley Thompson is certainly a hard act to follow but Macey is showing every sign that he could be a worthy successor to the crown.

The encouraging news for Macey is that world champion Tomas Dvorak - the man he identified as a major threat - looks far from his best and could still be suffering from injury.

Macey set a personal best in the long jump and ended up clinging on to third place before the 400 metres after a disappointing effort in the shot putt which was almost a metre below his best.

But the 22-year-old took comfort in the fact that his best events are still to come and Dvorak is not looking good.

Dvorak has a torn stomach muscle and has done well to come back from 12th where he was languishing after the 100 metres

Macey recorded a time of 10.81 seconds in the 100 metres which put him in sixth at that stage.

In the long jump, Macey measured in at 7.76 metres, in his bid to emulate Britain's two-time Olympic decathlon champion Daley Thompson.

Macey looked to be heading for trouble in the shot with a throw of 14.62 metres - almost a metre down on his best.

That left Macey 102 points behind America's Chris Huffins, who has led since the opening event. Estonia's Erki Nool was second - just 44 points adrift.

Dvorak is the red-hot favourite but he will have to improve dramatically if he is to stand any chance of taking the gold.

Macey has had his own injury problems with hamstrings and a troublesome elbow which needed two operations.

It almost seems too much to hope for afte Denise Lewis' efforts in the heptathlon - but it is just possible that the man from Canvey Island could strike gold.

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