Racing: Gavin Lang already won biggest race

Gavin Lang doesn't just feel lucky to be driving Auckland Reactor tonight - he feels lucky to be alive.

Australia's greatest reinsman will partner New Zealand's greatest pacer in the A$1 million Interdominion Final at Parklands tonight, where the pair face a horror draw from the outside of the second line.

But trying to weave a path to Interdominion glory from that near-impossible position will only be the second toughest challenge of Lang's summer.

A few months ago, just days after he turned 50, Lang feared he would never see 51.

He was struck down by a debilitating, yet mystery illness which put him in hospital for two weeks.

"I lost 8kg and the doctors found a huge lump, which they thought was a tumour," said Lang.

"I had no energy and I was the sickest I had been in my life.

"They did all the tests they could, took biopsies and even took bone marrow samples, but couldn't find a thing. I slowly started to get a bit better, so they let me go home and I picked up from there.

"But there were some pretty dark days when I didn't know what was going on."

Lang willed himself to get back in the sulky and soon returned to his natural environment - the winner's circle - in December.

Yet he couldn't have dreamed his road to recovery would carry him to the sulky behind pacing's most hyped horse in a decade.

With trainer Mark Purdon suspended and replacement Tony Herlihy committed to Gotta Go Cullen, Lang's aura has earned him the right to drive Auckland Reactor tonight.

Lang has never driven for Purdon; in fact they have been intense rivals for more than a decade.

Lang had never got near Auckland Reactor until a trackwork session on Thursday.

He flew to the Gold Coast for the dawn workout and left barely able to control his enthusiasm.

"He is a special horse, you can feel that," he said.

"Good horses feel different, and he feels that level up again.

"Mark is happy with the horse, and that is enough for me."

Lang is so respected in Australia he often gets asked to speak at functions about his career in racing. One question is asked more than any other.

"I get asked all the time: 'Who is the best horse you have ever driven'. After Saturday night I will have a new answer," he says in his laconic style.

His smile will disappear around midnight New Zealand time when Lang adopts his race face for the defining moment of his career.

While he has won three Interdominion Trotting Finals, Lang never finished closer than fifth in six Pacing Finals drives.

And he knows he will never get a better chance to win Australian pacing's Holy Grail than tonight.

He is definitely on the best horse but his problem is the two next best contenders, Blacks A Fake and Changeover, should settle in the two best spots.

Lang will need to make a quick decision.

He can rush forward early to try and blast past I Am Sam, who is likely to be parked and riding shotgun for stablemate Blacks A Fake.

Or Lang will have to show his legendary patience to sit and wait, a test of nerves on the tight Parklands track.

On a $10 million horse who is hot favourite in a A$1 million race in the one race he has wanted to win all his life, the pressure could be ear-splitting.

But it will be nothing compared with the real-life fears Lang faced in a Melbourne hospital a few months ago.