MELBOURNE (Reuters) - Novak Djokovic delivered a stinging lesson in the realities of grand slam tennis to young American Ryan Harrison on Wednesday and warned the next generation they need to work harder to break into the top ranks.

Novak Djokovic of Serbia hits a return to Ryan Harrison of the U.S. during their men's singles match at the Australian Open tennis tournament in Melbourne January 16, 2013. REUTERS/Daniel Munoz

The steely-eyed Serb's campaign for a hat-trick of Australian Open titles kicked into overdrive in the late match at Rod Laver Arena, as he demolished the highly-fancied 20-year-old 6-1 6-2 6-3 to charge into the third round.

"I definitely didn't want to underestimate my opponent tonight, even though he's younger than me, still didn't establish himself, you know, as a top 20 or top 30 player," the world number one told reporters after the 91-minute rout.

"But I still knew that he has a quality.

"Mentally he's probably going to go out on the court knowing he doesn't have anything to lose.

"He's going to try to smack serves and forehands. I went with that kind of mindset on the court, just trying to play as sharp as possible from the start, and I've done so."

Bullied on the baseline and broken early in each set, the 62nd-ranked Harrison scrambled hard to make a contest under the lights on centre court, but was left pinned at the back and stunned by Djokovic's shot-making.

It was a harsh reality-check for the American, who had pumped himself up like a prize-fighter prior to the match, talking of taking it up to the five-times grand slam champion.

Two breaks down into the second set, a punch-drunk Harrison was shell-shocked. He later conceded he felt powerless against a man with no perceptible frailty.

"Whenever your game plan is to try and take control of a guy and you're not getting balls to hit, you know, if I try to lace balls from six, eight feet behind the baseline I just look stupid and crazy," said Harrison.

"It's one where you're disappointed because obviously leading up the last day and a half, two days, I'm all excited because I'm wanting to make a statement, wanting to win this match, wanting to step up.

"I get stuck hitting six slices in a row, and then I'm running side to side and I look like I'm on a string."

Harrison said he would take a learning experience, however bitter, from the match. Djokovic warned him it was likely to be one in a long line of lessons.

"Well, we all know that the hard work and dedication pays off in the end," said the 25-year-old Serb, who will continue his bid for a sixth grand slam title and fourth at Melbourne Park against Czech veteran Radek Stepanek.

"But it's a process. And tennis has changed. It's much more demanding nowadays with the competition that is around the tour and many quality players.

"It's more difficult to make that breakthrough for a youngster. He needs patience and he needs to believe in himself and wait for a chance."

(Editing by Alison Wildey)

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