The constant fist-pumping, the shouts of "c'mon" and his sometimes overzealous on-court behavior didn't always impress fans or opponents -- but few ever doubted his quality or incredible desire.

"Lleyton was pretty brash and made some mistakes -- he knows he made a few growing up, nobody's perfect," his former coach Darren Cahill told CNN's Open Court.

"But he learned a lot from those mistakes. The one thing that defined him and why he's earned so much respect is that they know when he played for his country that he would leave everything he had on the court."

New kid on the block

Hewitt burst onto the scene as a 15-year-old at the Australian Open two decades ago.

Roger Federer, one of the greatest to have played the game, recalled that Hewitt was an "unbelievable teenager" and credited the Australian with helping his own career.

Others have not been so kind, citing his on-court behavior as one his rather less impressive traits.

In 2001, Hewitt was roundly criticized and fined $2,000 for calling a linesman at the French Open a "spastic" before offering an apology the following day.

A year earlier he had labeled the Australian public as "stupid" after being jeered during a tournament in his hometown of Adelaide.

Then there was the incident during the 2001 U.S. Open when Hewitt asked for a black linesman to be removed after being called for two foot-faults during his match against James Blake.

Wherever Hewitt has gone, there has always been controversy.

"Everyone is born with their own personality and I think I'm just born very competitive," Hewitt, now ranked 306 in the world, told Open Court.

"I would have tried to get the most out of myself in whichever path I chose to go down.

"I gave it 100% on the training track and on the matches as well, and I really brought that into my tennis.

"I wore my heart on my sleeve as soon as I came out there, but I believed in myself as well and I think that is one reason why I was able to have success at a young age.

"I believed that I belonged there and I was able to compete against the best guys."

Knock at the door

Cahill's first meeting with a 12-year-old Hewitt remains etched in his memory

"I got a call from his parents and then a knock on my door. There was this little kid with his hat on backwards and wearing a Nike outfit like Andre Agassi.

"He had the shorts over his knees, the Prince racquets -- he had about eight racquets in his bag.

"I don't think anybody at the age of 12 has eight racquets, but he was a total professional back then and that's all he wanted to be -- he wanted to be a professional tennis player."

From their first session together, Cahill says he could tell there was something special about Hewitt -- the determination and quick movement which would later frustrate the greatest of players was clearly evident.

Hewitt had already been taking coaching lessons from Peter Smith in Adelaide but with Cahill also on board, the young boy who had shown so much potential began to deliver.

He had always dreamed of playing at his home grand slam, where he used to watch the world's stars on the practice courts and then join the scrum to get hold of a souvenir headband.

The big stage

"I loved it there," Hewitt recalls.

"For me to get the opportunity as a 15-year-old was just a dream come true. I've had some of the my biggest highs on that center court and some of my toughest losses out there too -- but I wouldn't change it for the world."

Hewitt's first Australian Open experience was brief -- he was swept aside by Spain's two-time French Open winner Sergi Bruguera in straight sets.

A year later he won his first ATP Tour title at an event in Adelaide, beating Agassi in the semifinals.

At 550 in the world, Hewitt was the lowest-ranked winner in ATP history, and finished that season as world No. 100.

In 1999 the world really began to take notice of the blond-haired boy with baseball cap turned around the wrong way as Hewitt became the first teenager to win four titles in a season since Pete Sampras -- who would defeat him in the semifinals of the following year's U.S. Open.

No fear

"Lleyton wasn't scared of playing the top players in the world," Cahill says. "Most players, and I include myself in this, when you walk onto the court against the very best in the world, you're a little bit of a deer in the headlights.

"He was never like that. He was always hyped up and pumped up and had more belief in himself against the better players than he was when you sent him out to court 17 to play 'Billy Nobackhand' and 'Freddie Noforehand.'

"He did a remarkable job at a young age and for him to finish as world No. 1 two years in a row in the early 2000s was quite incredible."

Hewitt's ascent to the top of world tennis owed much to his remarkable victory at the 2001 U.S. Open.

Against Sampras, who had already won the tournament four times and would so again in 2002, Hewitt showed maturity beyond his years, sweeping aside the big-serving American 7-6 6-1 6-1.

"That match that Lleyton played in the U.S. Open final in 2001, I don't think I've seen anyone return serve better than that," Cahill says.

"If Sampras says Lleyton had the best return in the game in that era then it's coming from the expert because Pete's serve is still the greatest shot I've seen. "

Wimbledon winner

After winning the year-end finals and reaching No. 1 in the world, Hewitt won the coveted Wimbledon crown the following year, defeating Argentina's David Nalbandian in the final.

That would be Hewitt's last grand slam success, as he spent 80 weeks at the top of the rankings -- the 10th longest in the Open Era.

He was beaten by Federer in the 2004 U.S. Open final and, in front of his home fans, went down to Marat Safin in the title match of his next grand slam tournament.

Two more semifinal appearances followed in 2005, at Wimbledon and the U.S. Open, but Hewitt would never again go so deep in a major as he suffered a series of injuries.

But, whenever possible, Hewitt gave his all to Australia's Davis Cup team, spearheading its 2003 success to add to his first win four years earlier.

Nobody has played and won more matches in Australian Davis Cup history than Hewitt -- winning 42 singles matches and 16 doubles encounters since making his debut in 1999.

It is a fact which Cahill believes will define Hewitt's legacy.

"Lleyton will be remembered for his willingness to leave blood on the court when he had the green and gold jacket on," Cahill says.

"The Davis Cup epitomizes him, it's what we remember him for.

"He gave up a lot to play Davis Cup many, many times. He would take two or three months off the tour, make personal sacrifices -- the money, the points, the ranking, he would forget it all because there was a major Davis Cup tie coming up on a different surface and he wanted to make sure he was ready."

Final flourish

Hewitt's final Australian Open campaign will start against compatriot James Duckworth, a 23-year-old from Sydney, ranked 134 in the world.

Whether that will be his final match depends on his performance -- but the romantics will be hoping his farewell run goes beyond the first round.

"I didn't think I would be playing for 20 years," Hewitt reflects.

"When you come along you dream of playing in your national grand slam, and Australia has such a rich history in tennis because we are one of the grand slam nations.

"I qualified as a 15-year-old, it was just a dream come to true to actually walk underneath in the player areas and be a part of it.

"I still have to sort of pinch myself now."

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