The Leinster star has emerged as the most people's tip to fill the Lions' No 10 jersey against the Wallabies after a string of impressive performances for club and country.
Prior to damaging a tendon in his foot he had been suffering from a hamstring injury that forced him out of the defeat against England at the Aviva Stadium. He has not played since that game against England more than seven weeks ago.
"Jonathan Sexton has an outside chance of making Thursday's midday team announcement, but a return for the Ireland out-half is rated as being unlikely," stated a Leinster statement this week.
Leinster will have two-times British & Irish Lions tourist Gordon D'Arcy back in action after he missed last weekend's game through sickness, but his Test partner Brian O'Driscoll will miss the European encounter because of suspension.
Better news for Leinster is that Irish back row man Sean O'Brien is fit to resume after an extended lay off at the end of his arduous RBS 6 Nations campaign. His back row battle with James Haskell will be intriguing.