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The 143km he completed in the New Zealand 24-hour track championship in Auckland last weekend was just 3km short.
But it was a remarkable effort by the 51-year-old lecturer in English at the Otago Polytechnic, known to his friends as "Barefoot Bill," who was competing in the championship for the first time.
He was the fourth male athlete to finish and won the gold medal in the men's aged 50 to 59 grade.
Twelve men and six women competed in the event that was won by Alex McKenzie (Auckland), who completed 200km.
The world record by a barefoot runner is held by Dietmar Mucke (Germany), who ran 146km in 2005 when he was aged 43.
According to the Guinness Book of Records he ran the distance on an asphalt surface that is easier for a bare-footed runner than competing on a track.
Being so tantalisingly close to the record has encouraged Lucas to return for next year's event.
"Any kind of idiot can run a marathon but it takes a special type of idiot to race an ultra-marathon," Lucas quipped.
Lucas's inspiration to race the ultra-marathon started in the 1960s when he was a pupil at the Mornington Primary School when 90-year-old A. H. Reed gave a talk to pupils about his walk from North Cape to the Bluff.
Lucas started his barefoot training for long-distance events in 1998 because of the high cost of running shoes.
He trained for the event by running and walking the length of New Zealand over two summers - half one year and the rest the next year - in 2000 and 2001.
Lucas found that overcoming the mental gremlins was the hardest part of a 24-hour race.
"You can't train for an ultra-marathon. It's all about having the correct mental attitude and having the persistence to keep going."
Even the best runners can suffer from hallucinations during ultra-marathon races.
It happened to Lucas when he competed on the Otago Central Rail Trail.
It did not happen in Auckland but he did find himself listing to the left towards the inside of the track in the last six hours.
"They turn the runners around and run the opposite way around the track every four hours," he said.
"I began spiralling outwards and almost fell into the centre of the track."
His feet quickly became sensitised to the track surface.
"It was never uncomfortable and I did not get any blisters. But my feet became a bit red from the rubber surface."
McKenzie, the winner of the race, ran the whole way.
Lucas ran about half the distance and walked the rest.
"Only the world-class athletes can run the whole way in an ultra-marathon," he said.
The race started at 9.15am last Saturday and the most difficult part for Lucas was between 1-3pm.
The gremlins come for most runners in the early hours of the morning when the body metabolism is at its lowest.
"It was hot and windy during the day but the night was balmy and I started to perk up in the early hours. I did have a bad patch at 6am with just three hours left."
The event was organised by the Sri Chinmoy Hare Krishna sect that supplied food and refreshments throughout the race.
"I ate something after every three laps and drank 100 cups of tea during the race."
How did he recover?
"I did nothing but sleep on Sunday," he said.
"I had a few aches and pains and hobbled a bit when I returned to Dunedin."
Lucas kept a basin filled with cold water at the side of the track and he bathed his feet in it from time to time.
His wife Mami, who also runs, has a stress fracture at the moment.
His daughter, Albany (22), has recently started jogging again.