Roger Federer and Rafa Nadal will face the same question tomorrow when the Qatar Open begins the 2010 ATP Tour - can they possibly be what they were?

Tennis' two greatest heroes will want to answer that for different reasons - Federer, because of his apparent state of emotional bliss and Nadal because of his increasingly frequent physical problems.

Federer has the difficult task of finding new motivation now he has achieved every tennis goal of which he can ever have dreamed and gained a new focus in life with five-month old twin daughters.

Nadal needs to end a worrying eight months without a tour title and prove he can still challenge for Grand Slam trophies after what seems to have become semi-permanent knee problems.

Each player has been making optimistic noises, as they must.

Federer cites two new inspirations to sustain his very high standards whilst Nadal sees his immediate difficulties as stemming from other than a chronic injury.

Federer's scenario is the most innovative.

"I want the achievement of competing against three generations of players," he said, referring to his having started during the Sampras-Agassi era, continuing in "the Nadal era", and hoping to compete against the next wave of leading players.

"And I want to stay around long enough for my children to see me playing," Federer said, a remark suggesting the 28-year-old may try to remain at or near the top until he is 35. That is a tough ask.

But Nadal's scenario has more difficulties.

He may have under-trained, he volunteers, and for the first time agrees to succeed in future he may have to modify his schedule.

Because he helped Spain to victory in the Davis Cup final only four weeks ago, Nadal has had less than a month of close-season training and will, he believes, start this year in worse shape than last.

"I believe that this year I'll arrive a little bit less prepared than for the start of last season," he said. "My preparation has been short but good.

"I did get the chance to be with friends for a couple of days and I've spent some time with my family, so I'm really looking forward to the beginning of the season where I hope to regain my level of competition bit by bit."

Those last three words seem significant.

They suggest Nadal may not find it easy to start this year well, either in Doha or during the defense of his Australian Open title in Melbourne in little more than a fortnight's time.

Even more notable, he admits his arthritic knees may require him do what well-wishers have been advocating for a long time - reduce his clay-court schedule.

"I don't want to make the mistakes of the past season," Nadal said. "I had knee problems but decided to play anyway."

Nadal lost here last year in the quarterfinals to Gael Monfils, the explosively fast Frenchman; Federer was beaten in the semifinals by Andy Murray, who however won't be defending the title.

The Scot has preferred to go straight to Australia, in the hope that lengthier acclimatisation will provide a better chance of improving his modest early season record and perhaps of winning his first Grand Slam title.

Murray will be playing in the Hopman Cup mixed doubles exhibition event with teen hope Laura Robson.

Another leading Frenchman, Jo-Wilfried Tsonga, has withdrawn from the Qatar Open with an injured wrist, so if anyone is to prevent a Federer-Nadal final it is most likely to be Nikolay Davydenko.

The Russian caused a big surprise by winning the year-end ATP World Tour championships in London five weeks ago, overcoming Federer for the first time in 13 attempts in the semifinals.