Croatia's Marin Cilic has had his suspension for doping reduced from nine months to four by the Court of Arbitration in Sport, the International Tennis Federation announced on Friday.
Cilic, 24, currently ranked 47th in the world, tested positive for the stimulant nikethamide at the Munich Open in May and was banned by an independent tribunal in September.
The ban was backdated to May 1, meaning he would have been able to return to action on February 1, 2014.
However, the CAS ruled the ban should run for four months from June 26, meaning it now expires on Saturday Octoebr 26, leaving Cilic free to compete in the Masters 1000 tournament in Paris from next Monday, should he choose to.
"The CAS has partially upheld the appeal by Marin Cilic against the decision of the independent tribunal dated 23 September 2013," the ITF announced.
"The CAS panel decided that the independent tribunal's decision be set aside, and replaced with a period of ineligibility of four months, with the start back-dated to 26 June 2013, the date on which Mr Cilic accepted a voluntary provisional suspension. He thus will be eligible to participate on 26 October 2013."
Cilic, a former world number nine and 2010 Australian Open semi-finalist, provided a urine sample during the Munich event and an accredited laboratory in Montreal found it to contain nikethamide, which is on the WADA list of banned substances.
The Croat claimed he was unaware that Coramine tablets he bought contained nikethamide, for which he did not hold a valid Therapeutic Use Exemption.
"The substance in question originated from a glucose tablet purchased at a pharmacy in France. Unbeknownst to me, the glucose tablets contained a substance that is banned in competition," Cilic said in a statement at the time.
"I wish to emphasise 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."