LONDON -- Former top-10 player Marin Cilic has been suspended nine months for a doping violation.
The ban was backdated to May 1, so Cilic can return to competition Jan. 31, the International Tennis Federation said Monday.
Cilic tested positive for nikethamide, a stimulant, at a tournament in Munich last spring. The ITF said it accepted the player's contention that he ingested the substance inadvertently in glucose tablets and was not trying to cheat.
As a result, the ITF gave him a reduced penalty rather than a ban of up to two years.
Cilic plans to appeal to the Court of Arbitration for Sport. He said in a statement that he purchased the tablets at a pharmacy in France.
"I wish to emphasize that I have never knowingly or deliberately taken any banned substances in my life and that I am opposed to any use of performance-enhancing substances in sport," Cilic said.
The 24-year-old from Croatia has not played since withdrawing from his second-round match at Wimbledon in June, citing a knee injury. Cilic will be ineligible for the Australian Open in January.
He has been ranked as high as No. 9 in the world (in early 2010) after reaching the semifinals at that year's Australian Open. Cilic is currently 24th.
Cilic will lose all his results, ranking points and prize money since the Munich tournament. His best result in that span was a runner-up finish at the Queen's Club grass-court tournament, where he lost to Andy Murray.