Kooyong - Australian teenager Bernard Tomic beat France's Gael Monfils 6-4, 4-6, 7-6 (7/2) on Thursday to book a place in the final of the Kooyong Classic, a warm-up event for the Australian Open.

The 19-year-old, who is tipped to fill the shoes of ageing compatriot Lleyton Hewitt, will Saturday face either American Mardy Fish or Austrian Jurgen Melzer who play on Friday.

"I'm getting confidence this week for the Open and hope to carry it through," said the world number 37, from Queensland, who on Wednesday also claimed victory over top-ten ranked Czech Tomas Berdych.

"We came here for a good week and that's what I'm having."

The youngster showed his potential with a Wimbledon quarter-final last summer and reached last week's Brisbane semis before losing to Britain's Andy Murray.

Monfils, the world number 15, said he was troubled by a recurrent knee problem.

"I need to take care of my knee all of the time, I can hurt it with my movement," said the exuberant player.

"It was also cold at the start and then hot and my knee doesn't really like that."

Last minute stand-in Kei Nishikori upset Frenchman Jo Wilfried Tsonga 1-6, 6-4, 6-1.

Nishikori, whose 26th ranking makes him Japan's best male prospect in years, was drafted into the eight-man field at the four-day invitational event after Milos Raonic withdrew because of illness.

Tsonga made a lengthy trip after winning in Doha only to endure a miserable week so far, losing two matches in two days.

But the world number six remained bullish over his Open chances at Melbourne Park -- the first major of the season which starts on Monday.

"I have big expectations, but not because I won in Doha. I've expected to play well since I was a kid starting in the game, It's my dream to win a grand slam," said Tsonga. "I'm trying to improve my game to do that.

"I hope to make a push against the top four, if I can do that it would be something really big for me."

American Andy Roddick staged a comeback over Tomas Berdych and was relieved to win 4-6, 7-6 (7/5), 6-3.

"I need matches. I've had a long off-season, I was pretty banged up after 2011. I gave it a go today and got better as the match went on," he said.