Marin Cilic, pictured in 2013 in his first-round win before withdrawing due to a ban
Four years ago, Cilic was forced to withdraw from Wimbledon after a positive test for banned supplement nikethamide was revealed.
Cilic was given a nine-month ban, later reduced to four, and now has a chance to come full circle by beating Roger Federer in the final.
The Croatian had already knocked out Marcos Baghdatis in the first round of the 2013 Championships before being told of the ban.
Cilic said a member of his team had bought Coramine glucose tablets at a pharmacy.
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"Unbeknownst to me, the glucose tablets contained a substance that is banned in-competition (although it is allowed out-of-competition),” Cilic said 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."
An independent tribunal found that Cilic had inadvertently ingested the nikethamide as a result of taking the tablets and "did not intend to enhance his performance in doing so".
However, Cilic appealed the ban to the Court of Arbitration for Sport (Cas) and had it reduced from nine to four months.
Marin Cilic is now into his second Grand Slam final since the 2013 ban
"The panel determined that the degree of fault committed by the athlete was inferior to that established in the [tribunal] decision," Cas said in a statement.
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"The panel also determined that the sanction imposed was too severe in view of the degree of fault and concluded that it should be reduced to four months."
The panel still agreed that an anti-doping rule violation had been committed but said that Cilic had mis-identified one of the ingredients – confusing nikethamide with nikotinamid – which had led to it.