World number three Novak Djokovic sounded the alarm over the packed ATP calendar on Saturday after the withdrawal of two opponents helped him reach the final of an injury-hit Rome Masters.

- Djokovic, Wawrinka walk into Rome finals

Czech Radek Stepanek pulled out of his semi-final with Djokovic on Saturday less than 24 hours after Spaniard Nicolas Almagro's retirement had put the Australian Open champion into the last four. Stepanek, who had upset world number one Roger Federer [Images] on Friday, was 6-0, 1-0 down.

"This is another showing that the season is really tough. The players are not getting injured for nothing," Djokovic told a news conference.

Top American Andy Roddick [Images] also retired early in the other semi-final against unseeded Swiss Stanislas Wawrinka with a back injury. Roddick was 3-0 down in the first set.

Furthermore, Almagro had been awarded a walkover to the quarter-finals after Chilean Fernando Gonzalez, last year's runner-up, pulled out of their third-round match with a leg injury.

"The players at the top and the ones who are playing a lot of matches are not happy with the schedule this year," Djokovic said.

"We are well aware of the fact that the Olympics [Images] are making it even more difficult, but this is something that we will need to talk about in the future.

"I'm not criticising anyone, but it's very important to take care of the players. We don't want to have these kinds of situation at big events, the players retiring in the semi-finals and quarter-finals after one set," the Serbian added.

Djokovic's comments echoed those of world number two Rafael Nadal [Images], who called the calendar "impossible" on Wednesday after playing with a foot problem during his shock second round defeat by fellow Spaniard Juan Carlos Ferrero.

Roddick said it was probably a coincidence that so many players had been injured in Rome, but agreed that the calendar needs to be lightened.

The ATP said in a statement they noted the concerns and said reforms to the calendar in 2009 would offer players "a fairer and healthier schedule".

"As in 2004, we are aware that this year's calendar asks a great deal of all ATP players in terms of scheduling for the European spring clay court season," said Andy Anson, ATP CEO of Europe.

"Combined with the Olympics in August, this makes for a challenging season for all. However, these challenges underline why the ATP has made the re-structuring of the ATP calendar a priority.

"Our wide ranging changes to the existing season, combined with a new Davis Cup schedule, will ensure that the unique situation of an ATP calendar that contains shortened clay and summer hard court swings is not repeated in future years."

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