But after intensive treatment he now has a chance to figure in the expected 20,000 sell-out clash against the Tigers - a game that will determine who will top Pool 3 and reach the quarter-finals.
"The injury has improved quite a lot from the weekend. I still have time on my side and this is a game I don't want to miss," said Byrne.
"I was in a lot of pain in Perpignan, but that has subsided and hopefully I can play on Saturday and help the Ospreys to make history by qualifying for the quarter-finals again.
"With a likely full house at the Liberty Stadium it would be a great game in which to prepare for the Six Nations with Wales. Heineken Cup rugby is right up there with the international game.
"I really don't want to miss out and my only thoughts are about making sure I get into an Ospreys jersey this weekend."
Ospreys coach Sean Holley confirmed his star full back is fit again after his injury. While he is 'hopeful' he will be able to pick him at the weekend, the news on another of Wales' 2008 Grand Slam heroes, Jonathan Thomas, is not so encouraging.
"Jon is undergoing a review and is doubtful for the Leicester game at the moment.