Lincoln Tighe just wanted to let his mates know he worked on his legs at the gym on Wednesday. They reckon he only ever hones the upper body, the one which has his long ball the talk of the Australasian tour each summer.

"Put that in there because all the boys think I don't train legs," laughed the Wollongong-raised Tighe, the surprise Australian Open leader after players sweltered at The Australian Golf Club during the first round.

What he lifts is anybody's guess, though. Tighe knows. But unlike the pride in his driver - which carries 300 metres regularly - the bench press number wasn't exactly forthcoming.

What is a little clearer is how the kid who only needed to turn 11 before managing to out drive his dad Darryl - an ally in Tighe's small gallery on Thursday and still playing as a five marker - has turned his once stocky frame as an 18-year-old amateur into one of the most chiselled on tour.

"I was a bigger guy and never really looked like this and my mate gave me a bit of a wake-up call and said, 'in this day and age with golf and just in everyday life you need to be fit'," said the world No.1022, whose opening round five-under 66 had him a shot clear as the clubhouse leader heading into Friday's second round.

"I was 115 kilos, but I got down to 88 and now I'm about 98 as I've tried to slowly build it back up and put some muscle on. I've always been [a] long [hitter], but I've found since I've started training five days a week I've stepped it up and am a lot more consistent."

A talented pre-teen in both tennis and golf, it was the latter which eventually held sway for Tighe after years shadowing his father. Darryl is better known to the good folk of the Illawarra as the bloke who owns that jewellery store in Dapto Mall. His son was quickly off a handicap of three as a 13-year-old when pouring all his energy into a club rather than racquet. Whether Darryl has a special engraving in store for a Stonehaven Cup winner 13 years later will be left to the weekend.

But what won't change is his son's mental approach. Several times before his near blemish-free opening round - which saw him get hot late with four birdies in the space of five holes to touch six under - he reminds himself before a shot it doesn't matter. Not if it is good. Not if it is bad. Not if it is indifferent.

"You need to just realise if you miss a putt or miss a shot you still get to go home [at the end of the day]," the 26-year-old said. "I just say, 'it doesn't matter'. I say it before [addressing the ball]. Not every shot, but sometimes."

The 20-year member of Port Kembla was still pinching himself when asked to do a barrage of interviews on Thursday afternoon. He couldn't even get a start in the pro-am on the tournament eve - and thought he probably didn't "deserve" one either given the calibre of the field for the 100th national championship.

Many an unheralded hope has been in this situation though, a one-day wonder weaned out of the public conscience by the weekend. But with his unparalleled length off the tee - which had him chipping onto the 10th green after a first drive he thought he "necked" into the 381-metre par four - The Australian's searching layout suits just fine.

"It's unreal. I wish I finished at six [under], but if someone said to me at the start of the day you're going to be under par in these conditions I would have taken it," Tighe said. "To shoot five [under] and play solid was great. I'll stick to my process and routine and whatever happens happens."