Rafael Nadal insists the memory of seeing his 81-match winning streak on clay broken by Roger Federer in the final of last year's Hamburg Masters Series will ensure history is not repeated.

The 21-year-old was denied a historic sweep of the clay ATP Masters Series titles as Federer won his fourth Hamburg title, 2-6, 6-2, 6-0 last year and Nadal is determined not to let it happen again.

"The motivation will be there for me as soon as I enter the stadium," the Spaniard told the Sunday edition of Die Welt.

"I will always remember losing the 2007 final, because on the one hand the defeat stopped me profiting from winning the title and also my run of wins on clay was broken.

"But I must say, I have a good memory of the tournament from a year ago: I lost in the final against the best player of all time."

Although Federer and Nadal have dominated the men's game for nearly three years, Nadal insists 2008 Australian Open winner Novak Djokovic, who won last week's Rome Masters Series, is the player to watch in Hamburg.

"He is playing very well at the moment," said Nadal, who crashed out of the Rome tournament in the second round. We knew already he could become a great player.

"But for some, his victory in Australia came sooner than expected."

Nadal suffered only his second defeat in 105 matches on clay when he lost 7-5, 6-1 to Juan Carlos Ferrero in the second round in Rome last week.

He was seeking his fourth successive title in Rome, but struggled with a foot blister and the loss comes after Nadal complained recently of an overcrowded schedule.

With the addition to this year's calendar of the Olympic Games in August, the clay-court schedule has been squeezed and left Nadal playing consecutive weeks in Monte Carlo, Barcelona, Rome and next week in Hamburg.

The Hamburg organisers will be hoping their event is not affected by injuries like those seen in Rome last week.

Djokovic criticised the packed ATP calendar last Saturday after a second withdrawal of an opponent helped him reach the Rome final.

Radek Stepanek pulled out from his semifinal with the world number three, 24 hours after Nicolas Almagro retired against the Serb in the last eight.

Andy Roddick, who is also out of Hamburg, also had to quit early in the other semifinal against Stanislas Wawrinka with a back injury.

Djokovic said: "The players are not getting injured for nothing."

Former world number one Marat Safina is in the main draw after winning both his qualification games over the weekend and will be aiming to emulate his sister's success in Germany after Dinara won the German Open in Berlin on Sunday.