Former world 100m record holder Asafa Powell and fellow Jamaican Sherone Simpson have had their doping bans reduced from 18 months to six months.
The ruling by the Court of Arbitration for Sport (Cas) means the sprinters are free to race again immediately.
Powell plans to run at a meeting in Lucerne on Tuesday.
Powell and Simpson, who has won Olympic relay gold, both tested positive for the banned stimulant oxilofrine at last year's Jamaican national championships.
Powell, 31, called the initial suspension "unfair and unjust".
|Asafa Powell facts|
|Personal bests: 100m - 9.72 secs; 200m - 19.90 secs|
|Medals: Olympics: 4x100m relay - gold (2008); World Championships: 100m - bronze (2004, 2008), 4x100m relay - gold (2009), silver (2007)|
He wrote on Twitter: "Finally this weight has been lifted off my shoulders. Justice has been served. Now let's run!"
Powell and Simpson, 29, were given 18-month suspensions by the Jamaican anti-doping disciplinary panel in April, though both were backdated to end in December 2014.
Both argued their offence was minor because the positive results came from taking a contaminated version of Epiphany D1, a legal supplement.
In January, Powell testified that physical trainer Chris Xuereb provided him with nine supplements, including Epiphany D1.
Canadian Xuereb denies the claims.
|What is oxilofrine?|
|A stimulant drug banned by the World Anti-Doping Agency, the substance is an amphetamine found in some dietary supplements|
|It was developed to treat low blood pressure|
|The substance is thought to allow people to burn fat faster and lose weight, which is why it is present in some so-called sports nutrition supplements|
|It can also increase the rate at which the heart reaches its maximum performance during exercise|
|But Professor Wayne McLaughlin of Caribbean Toxicology told Powell's trial that oxilofrine "does not improve speed"|
Powell, the biggest name in Jamaican sprinting before the rise of double world and Olympic champion Usain Bolt, held the 100m world record between 2005 and 2008.
Training partner Simpson won silver in the 100m at the 2008 Olympics and also has Olympic gold and silver medals from the sprint relay.
Both athletes will miss the Commonwealth Games in Glasgow as the Jamaican team was selected during their suspension.