British number two Aljaz Bedene says he has a "strong case" to put before the panel that will decide on Sunday if he can represent Great Britain.
Bedene, 26, played three Davis Cup ties for Slovenia before becoming a British citizen in March 2015.
That was after the International Tennis Federation introduced a rule preventing players from representing more than one country.
"I've got a strong case, and I'm still positive," Bedene told BBC Sport.
The case will be heard in Moldova, with Bedene appearing by video link from Irving in Texas, just a few hours before competing in the final of a Challenger event.
Bedene is appealing on the grounds his passport application was lodged before the rule was altered at the start of 2015.
The hearing was originally scheduled for Prague in November, but the ITF postponed it - after Bedene had arrived in the Czech Republic - to "ensure the rights of all parties are considered".
The Lawn Tennis Association was frustrated by the delay and Andy Murray - who feels Bedene should be eligible for Davis Cup and Olympic Games selection - described it as a "bit disrespectful".
"I've been waiting for a year and a half now," said Bedene, who was a practice partner during Britain's Davis Cup tie with Japan earlier this month.
"I'm quite nervous - I really want it to be successful. I've got my own 15 minutes over Skype at 5 or 6am, but I'll wake up to do that and try to convince them."
The Lawn Tennis Association is, privately, talking down its chances, and if the hearing ends in disappointment, Bedene's last option will be an appeal to the Court of Arbitration for Sport, which seems a likely course of action.
"It's a tough one," he said. "If they would say at the beginning 'No,' straightaway, no complications, I would accept that, but it's been taking way too long, and yes, that's the next step."