The International Tennis Federation (ITF) has withdrawn a doping violation charge against American player Maksim Tikhomirov due to a lack of evidence.
The 30-year-old was charged with evading sample collection on May 5.
It was alleged that on January 28, Tikhomirov failed to acknowledge notification of selection for testing by failing to sign the notification form, and failed to provide a sample following that notification.
This would have constituted an anti-doping rule violation under article 2.3 of the ITF anti-doping programme.
Following a review, the independent tribunal determined that there was insufficient evidence to confirm that a violation was committed.
Tikhomirov, who accepted a voluntary provisional suspension on May 20 pending resolution of his case, is free to compete with immediate effect.
Both the World Anti-Doping Agency and the United States Anti-Doping Agency have the right to appeal the decision, however.
Tikhomirov is currently 614th in the Association of Tennis Professionals world rankings.
He reached a career high of 583 earlier this year.