(CNN) -- American Robert Kendrick, ranked 105 in the world, has been banned from tennis for a year after testing positive for banned stimulant methylhexaneamine during May's French Open.
The 31-year-old Kendrick, who lost in four sets to Spain's Guillermo Garcia-Lopez in the first round at Roland Garros, will not be able to return to action until May 22, 2012, after his ban was back-dated to the day of the offence.
The International Tennis Federation (ITF) accepted Kendrick's claim that the stimulant was in a capsule he took to combat jetlag and was not intended to enhance his performance.
However, the Tennis Anti-Doping Program makes it clear it is up to each individual player to ensure that no prohibited substance enters their body.
An ITF statement confirmed: "The ITF announce that Robert Kendrick has been found to have committed a Doping Offence under Article C.1 of the Tennis Anti-Doping Program.
"Mr Kendrick provided a sample on 22 May 2011 at the French Open held in Paris. That sample was sent to the WADA-accredited laboratory in Montreal, Canada for analysis, and was found to contain methylhexaneamine, a stimulant.
"Methylhexaneamine is a prohibited substance under section S6 of the 2010 WADA List of prohibited substances and is therefore also prohibited under the Tennis Anti-Doping Program. Mr Kendrick was therefore charged with an anti-doping rule violation under Article C.1 of the Program."
Kendrick, who reached a career-high of 69 in the world in 2009, has never won an ATP Tour title and never got past the second round of a grand slam event.
However, he took the first two sets against Rafael Nadal in the second round at Wimbledon in 2006 before eventually going out.
Meanwhile, in tennis action on Friday, three of the top four seeds are through to the semifinals of the Gstaad event in Switzerland.
Top seed Nicolas Almagro joined fellow-Spaniard Fernando Verdasco, seeded four, and Russian third seed Mikhail Youzhny in the last four.
However, second seed Stanislas Wawrinka disappointed the home fans by losing 6-3 6-2 to eighth seed Marcel Granollers, ensuring three Spaniards reached the semis.
There was a major surprise in the WTA tournament in Stanford as top seed Victoria Azarenka was beaten 4-6 7-5 6-2 by New Zealand's Marina Erakovic.
However, local favorite Serena Williams claimed a hard-fought 6-3 3-6 6-2 win over Maria Kirilenko of Russia to set up a last eight showdown with Maria Sharapova.