(CNN) -- World No. 2 Novak Djokovic has revealed that he is no longer working with American tennis coach Todd Martin following a disappointing eight-month partnership.
The Serbian brought in Martin to work alongside his other coach Marian Vajda before last September's U.S. Open, a tournament in which the 39-year-old was a finalist in 1999.
Martin has mainly worked with Djokovic in American events, but the 22-year-old lost in the last 16 at Indian Wells last month and was then beaten in his opening match in Miami a fortnight later.
Djokovic, who retained his Dubai title before the first U.S. hardcourt swing of the 2010 ATP Tour calendar, is now looking to regain his form on clay in Monte Carlo this week.
"I'm no longer working with Todd Martin," the top seed told reporters on Monday. "Todd found it difficult to understand who I am, how I like to work. It seems there will always be a problem having two coaches.
"Todd has specific ideas on some issues of work. There were no major problems, but changes in my service did not work out. It was a good experience and I'm not sorry for it."
Martin, who also reached the final of the Australian Open in 1994 and reached a highest ranking of fourth, retired from the elite level in 1999 and now plays on the seniors' Outback Champions Series.
Djokovic has a first-round bye at the first event of the European clay-court season, and is scheduled to begin his campaign against either Florent Serra or fellow Frenchman Stephane Robert.
He lost last year's final to Rafael Nadal, who is seeded second as he seeks to restore his status of "King of Clay" after a year wrecked by injuries.
"He's been so dominant for so long on clay, but everyone knew that just couldn't last," said Djokovic, who was also beaten by the Spaniard in last year's Rome final -- Nadal's last tournament win.
"But his level is now down just a bit and others are starting to get confidence and the belief that they have a chance to beat him."
World No. 4 Andy Murray is also hoping to bounce back in Monaco after also losing his first match in Miami.
The Scot's former mentor Leon Smith has been named as Britain's new Davis Cup captain to replace John Lloyd, who quit after the team's embarrassing defeat by Lithuania last month.
Murray decided not to play in that match, but Smith said he would not put pressure on the 22-year-old to return against Turkey in July.
"He'll make his decision again on a tie-by-tie basis and I'll respect if he decides to play or not play," Smith told the UK Press Association on Monday.
"I fully support that he has got wider things to do in tennis. He's ambitious, he wants to win a slam and I respect that."
Smith, who won the job ahead of candidates including former world No. 4 Greg Rusedski, worked with Murray while he was a junior player.