Tennis is to step up its anti-doping efforts with increased testing and more samples stored for potential reanalysis.
In the week of Maria Sharapova's return to the sport following a 15-month doping ban, tennis' governing bodies have approved enhanced measures for the Tennis Anti-Doping Programme from May 1.
A total of 8,000 annual samples will be collected compared to 4,899 in 2016, covering more urine and blood samples both in and out of competition and an increased testing pool.
Up to 50 per cent of the samples for top-ranked players will be placed into long-term storage, allowing them to be retested when new or more sensitive detection methods become available.
To fund the changes, the annual budget for the programme - which is funded by the ATP, WTA, International Tennis Federation and the four grand slams - will increase by more than 50 per cent to around 4.5million US dollars (£3.5million) in 2017.
ITF president David Haggerty said: "On behalf of the partners in the Tennis Anti-Doping Programme, we welcome this strengthening of the sport's anti-doping efforts.
"Protecting the integrity of tennis is an ongoing priority of the governing bodies of tennis to ensure that tennis is and remains a clean sport, and these enhancements will make a positive contribution to achieving that priority."
