Dominant Federer through to Doha final

DOHA (Reuters) - An ailing Rafael Nadal slumped out of the Qatar Open Friday to deprive fans and organizers of an eagerly-anticipated final against his great rival Roger Federer.

Federer kept his part of the bargain with a 6-3 7-6 defeat of Jo-Wilfried Tsonga in the first semi-final at the Khalifa Tennis Center but Nadal withered away after a bright start against Russian defending champion Nikolay Davydenko, losing 6-3 6-2.

It was an emphatic loss for the world number one, who was also beaten here last year by Davydenko, but he was clearly suffering with his condition, telling an on-court doctor he felt "terrible" during the second set.

From 1-2 down in the opening set, Davydenko turned the match around in stunning fashion with some pinpoint hitting.

Nadal lost eight consecutive games from 3-3 in the opening set but roused himself briefly to avoid his second 6-0 set of the tournament, snatching a break of serve before Davydenko closed out the victory.

"Tomorrow I need to have good legs and run and control the ball. Maybe my tennis is a little better than last year."

Nadal, who has been suffering with a fever all week in the Qatari capital, showed guts to finish the match in the circumstances but will be keen to regain 100 per cent fitness before the Australian Open that starts later this month.

The 16-times grand-slam champion produced an almost perfect serving display to keep the hard-hitting Frenchman at bay.

Even when Tsonga did start to unwind in the second set there was no rattling the Swiss who at one stage clocked up 14 consecutive points on his service.

"I played well. It became a high quality match in the second set and it was right that it went to a tiebreak because Tsonga played well too."

Federer has a 14-2 career record against Davydenko, although he did lose to him in last year's semi-final before the Russian beat Nadal in the final.

(Additional reporting by Regan E. Doherty)

(Writing by Martyn Herman; Editing by Clare Fallon and John Mehaffey)