DUBAI (AFP) - Novak Djokovic defeated Tomas Berdych in three sets in the Dubai Open on Friday to earn a shot at his 50th title and an opportunity to atone for last year's loss to Roger Federer.

The world No. 1 from Serbia won 6-0, 5-7, 6-4 against the former Wimbledon finalist from the Czech Republic in a lengthy and unpredictable semi-final which began as high speed one-way traffic.

Djokovic started so brilliantly that he won the first set in only 23 minutes, then the first seven games and even went a break up early in the second set, at which stage he seemed unstoppable.

Remarkably however he forced Berdych to play so well that when his own level dropped, he found himself slipping into difficulty.

Berdych began to serve well, to focus even harder and to hit some rousing ground strokes, and in the third set when he got Djokovic at deuce on one of his service games and at 15-30 on another it seemed he might even tilt the see-saw to its full opposite.

The third phase saw Djokovic hang on tight, break for 3-2 with the help of one deftly angled dink made while running at full speed, and grittily negotiate every subsequent crisis.

By then he had morphed into a hungry fighter who was quite different from the Midas-touched genius who started the match.

"When you feel as good on the court as I felt for the first 30 minutes, there's not much you're thinking of. You're in the present moment and you're swinging through the ball, and everything works as well as you want," said Djokovic.

"But then of course you're going to come to the stage where you're going to get tested, especially when you're playing a quality player like Tomas," he added, recognising that Berdych has had his best start to any season.

Djokovic concluded: "It's a win that I'm happy about and hopefully I will be able to start tomorrow (Saturday) as well as I did today, you know - and maintain that rhythm, because that will be necessary in order to win against Roger."

The Grand Slam record-holder has indeed looked in very good order - despite having come straight from two weeks' vacation - and advanced confidently to his ninth final here and the 123rd final of his career.

Federer did that by winning 6-2, 6-1 in less than an hour against Borna Coric, the teenager who practised with Djokovic, and is now being touted as a future champion.

The 18-year-old Croatian only reached the main draw as a lucky loser, but then became the youngest player ever to reach the semi-finals here when trampling win over Andy Murray, the world number three.

But Federer taught the surprising upstart a sharp lesson.

His ability to mix up the patterns with slices, paces changes and net rushes, and to break the rhythms of containment at which Coric had previously excelled, made it more difficult for the rookie to overcome his tension.

Coric showed hints of humour to leaven his disappointment. "I was watching him when I was six or seven and hoped I would one day play him," he said. "I knew it would be difficult and there is more pressure than when you are watching on the sofa."

But Federer knew all about that, and even more about the pressures which Coric is now likely to have heaped upon him.

"I remember when I played Andre Agassi when I was 17," Federer said. "I was scared I would lose love and love and I won five games, and that's how it goes. I wish Borna well for the rest of his career.

"I can see why he has caused difficulty for a lot of top guys, and there is room for improvement. But don't make him the next Novak (Djokovic). Don't do that to him."