Sitting out last week's Miami Open enabled Novak Djokovic to make himself available to the Serbian Davis Cup team said the world number two on Tuesday (April 4).

Djokovic missed the Masters series event with an elbow injury and, having recovered, is eager to face Spain in the Davis Cup quarter-finals in front of a boisterous home crowd next weekend.

But Rafael Nadal's fine current form, having reached both the Miami Open and the Australian Open finals - and lost to Roger Federer in each, means he is giving the Davis Cup event a miss while he prepares for clay court play.

Djokovic said that he is eager to play and welcomes Davis Cup matches as a path to return to form, even if the hard court set up for the duel with Spain is not ideal ahead of the season on clay.

His maiden French Open title last June marked the start of a dramatic loss of form for Djokovic, who has dominated for several years, racking up 12 grand slam tournaments. He was eventually ousted from the world number spot by Briton Andy Murray.

With Murray also playing in fits and starts in the early stages of the season, Djokovic heaped praise on the evergreen Roger Federer after the Swiss maestro won the Miami Open following his Australian Open triumph in January.

Federer demonstrates that "oscillations" in top-level careers are a "natural flow of things," but also that players can recover and return to the top at a mature age.