England wing Ben Cohen could miss the entire Premiership season after his proposed move to Leicester fell foul of English rugby's financial regulations.
Cohen is England's equal second-highest try scorer of all time with 31
The 29-year-old bought himself out of his Northampton contract so he could join the Tigers, but his testimonial earnings would have to go with him.
And that would force Leicester to exceed the Premiership's salary cap.
"It's beyond our control and we can't afford it," Tigers coach Richard Cockerill told BBC Radio Northampton.
Cohen's testimonial year at Northampton, where he spent 10 years, is expected to raise around £300,000.
If that figure was combined with the earnings of the other players already at Leicester it would take the Tigers above the permitted figure of £2.182m for a first-team squad.
It's just intensely frustrating that a player is unable to ply his trade because he's been rewarded for his loyalty to one club
Players' representative Damian Hopley
Premier Rugby manager Phil Winstanley sympathised with Cohen's plight, but offered little encouragement the matter would be resolved in the winger's favour.
"We don't want to stop Ben playing rugby, that certainly isn't the intention, but under the rules testimonial earnings are salary," said Winstanley.
"He hasn't been with Leicester long term, so they wouldn't be entitled to a dispensation not to include those earnings.
"They need to determine if they have sufficient space in their salary cap to accommodate Ben."
When asked for Leicester's reaction Cockerill added: "Were we interested in him? Yes. Is that going to happen? No, because we can't afford it. It's unfortunate but we have to abide by the rules."
Professional Rugby Players' Association chief executive Damian Hopley added that plans were under way to act on Cohen's behalf, but was also cautious.
"We're exploring every possibility and have spoken to a number of lawyers about how we can challenge the salary cap regulations," he said.
"But even if we were successful it would be well after the season has finished. It's just intensely frustrating that a player is unable to ply his trade because he's been rewarded for his loyalty to one club."
England winger Cohen, part of the 2003 World Cup-wining side, missed this year's World Cup for family reasons and has yet to play this season.
Cohen has won 57 caps for England and is the country's second-highest try scorer of all time, alongside Will Greenwood, with 31.