Young and hungry, five who could fire in Melbourne

Alexander Zverev of Germany is seen as a trailblazer of tennis's widely touted "NextGen". (Photo: AFP/Tony Ashby)

GRIGOR DIMITROV

The 26-year-old Bulgarian heads to Melbourne a dizzy third in the rankings behind only Rafael Nadal and Roger Federer. Nicknamed "Baby Fed" early in his career for his Federer-style game, Dimitrov has struggled to live up to the comparison and was as low as 40 in the world in mid-2016. But he bounced back to enjoy the best season of his career in 2017, winning four titles, including his first Masters crown in Cincinnati. Dimitrov has the task this year of defending his rankings points and backing up a top-five season. He has never been beyond the semi-finals of a Grand Slam, reaching the last four at Wimbledon in 2014 and repeating the feat in Australia last year.

ALEXANDER ZVEREV

A giant young German who is seen as a trailblazer of tennis's widely touted "NextGen". The 20-year-old heads into the year's first Grand Slam ranked fourth, and is coming off five titles last year. Zverev is one of just four men to beat Federer in 2017 when he defeated the Swiss great in the Montreal final. But Zverev has never made it past the fourth round of a Grand Slam, and he's reached that stage only once, at Wimbledon in 2017. Gets enormous power off his 1.98 metre frame and pundits say as he bulks up and gains more experience in five-set matches, success at all tournaments, including Grand Slams, should follow.

DOMINIC THIEM

The 23-year-old Austrian finished the 2017 season with a title on clay in Rio de Janeiro and a year-end fifth ranking. Thiem claimed his first win over Novak Djokovic at the French Open quarter-finals on the way to reaching the semi-finals at Roland Garros for the second straight year. His boyhood idols were countrymen Stefan Koubek and Jurgen Melzer, while his favourite shot is the forehand and he prefers to play on clay. Thiem, who pulled out of the warm-up Qatar Open ahead of his semi-final with flu, finished 2017 by making his second appearance at the ATP Finals in London.

NICK KYRGIOS

A volatile Australian whose potential has often been betrayed by his temperament. He brought last season to an early end when he surrendered to a long-standing hip injury, but has started 2018 in top form, winning the Brisbane International on Sunday (Jan 7), beating Dimitrov along the way. Kyrgios is aiming for a fresh assault on his home Grand Slam, where he threw away a two-sets lead to lose to Andreas Seppi in the second round last year. The 22-year-old crowd-puller, ranked 17, has the exceptional talent to beat the best but so often undermines his brilliance with petulance directed at the umpire or fans. Has two career wins over Rafael Nadal. Remains a danger man if his hip and attention span hold up.

ANDREY RUBLEV

The 20-year-old Russian captured his first ATP World Tour title as a lucky loser at Umag before he became the youngest US Open quarter-finalist last year since Andy Roddick, beating Grigor Dimitrov and David Goffin before going down to world number one Rafael Nadal. Now ranked a career-high 32, the run in New York solidified Rublev's status as one of the top "NextGen" ATP players in the world.