By Ian Ransom

MELBOURNE (Reuters) - With firebrand Nick Kyrgios Australia's top hope at the year's first grand slam, local fans may be set for a thrilling, if occasionally bumpy roller-coaster ride at Melbourne Park.

Kyrgios, a 21-year-old with a temper as prodigious as his talent, brings a 14th seeding and a growing esteem from higher-ranked tour rivals despite his explosive tantrums and long rap-sheet of on-court transgressions.

His last major meltdown occurred at the Shanghai Masters in October, for which he was fined $25,000 and suspended for eight weeks after clashing with fans, the chair umpire and walking off court in the middle of a point.

The outburst came just days after he won the Japan Open, his third title in a year of impressive growth and improvement, histrionics aside.

Drama never seems far away far away from Kyrgios and his leadup to Melbourne has been blighted by a knee problem which saw him limp through the Hopman Cup in Perth.

He has been salving it with cortisone patches but insisted on Saturday that he would be fit enough for his first round match against Portugal's Gastao Elias.

"Yeah, it's feeling really good. I've done four or five treatments on it," Kyrgios, a quarter-finalist at the 2015 tournament, told reporters at Melbourne Park.

"Got one more tomorrow. Yeah, it's feeling a lot better since I last competed, which was in Perth. So I've had massive improvements in my knee."

Kyrgios's knee problems have added to fitness concerns about Australia's number two Bernard Tomic, another player with a record of poor conduct both on and off the court.

Neither player has ever sounded enthused about reaching Andy Murray-like levels of fitness and Tomic, seeded 27th in Melbourne, has raised alarm bells over his weight, firstly for being too heavy and then for going on a crash diet.

STOSUR'S STRUGGLES

Tomic, who plays Brazil's Thomaz Bellucci in the first round, said he had shed 4.5 kg in a week, having been too "fat" at the Brisbane International, where he lost his opener against Spain's David Ferrer.

"There are some players not as fit as me inside the top 10, 15 in the world," the 24-year-old told reporters at Melbourne Park on Saturday, quickly wearying of the continued attention over his weight.

"Will fitness help them? I don't think so."

Former U.S. Open champion Samantha Stosur, as ever, remains Australia's top hope in the women's draw but has always suffered from crippling nerves in the spotlight of her home grand slam, where she has never surpassed the fourth round.

The 32-year-old, who meets Briton Heather Watson in the first round, remains a formidable player on her day and turned back the clock with a run to the semi-finals at the French Open last year.

But she is in the midst of a huge form slump, having not won a tour match since reaching the second round at the U.S. Open.

Australian women's number two Daria Gavrilova, who plays another Briton in Naomi Broady, may be better equipped to go deep, having fed off the crowd fervour on a run to the fourth round last year.

"I'm not really thinking about last year too much, but I know that it was pretty cool times and I had big crowds," the Russia-born 22nd seed told local media.

"That's all I play for."

(Editing by John O'Brien)