A candidate to captain the 2013 British & Irish Lions, O'Driscoll has taken 10 weeks of painstakingly precise rehabilitation to make it back in time for one PRO12 League outing before Leinster embark on an unlikely mission to save their Heineken Cup crown.
The 33-year-old has managed to make it back two weeks earlier than originally estimated from surgery on his ankle ligaments at the end of October.
The outstanding outside centre looked set fare for a stellar 10 months, with the Lions tour a gold-coloured Australian carrot at the end of the season, maybe his last season.
He was just getting into a rhythm from his six-match impact for Leinster when he was taken out of the series of November internationals and the critical back-to-back epic matches against Clermont-Auvergne in the Heineken Cup.
O'Driscoll has made a career out of defying the odds. He could almost have been talking about himself when he spoke about Leinster's Heineken Cup peril at Christmas.
"We will not go down without a fight. You can be absolutely sure about that. It is stacked against us. But, never-say-never," he said.
"We've got a mentality now that we are relentless and that we never give up. We'll see what comes of that in the end."
Ultimately, he has beaten the guess-timation of the specialist to take his place in the centre of Leinster's attack and defence against Edinburgh.
For Kearney, he has had to manage the return to fitness alongside his long-lasting frustration about a back problem that troubled him on-and-off over seven years.
"I have been dealing with this problem for a long time. I first got it on St Stephen's Day 2005 against Ulster at Ravenhill," he said, back in November.
"It has been bothering me since but it got really bad last year. It put me in doubt for the week of the Heineken Cup final last season.
"When I went on tour to New Zealand in June, it got worse and worse. It probably should have been looked after then. But it wasn't. If I am back in January I will consider that a pretty good return."
The Louthman's application to his rehabilitation has been rigorous, initially involving a mind-numbing two-to-three weeks off his feet.
Kearney is in a good position to contribute to rounds five and six of Leinster's Heineken Cup and Ireland's Six Nations and the Lions, for which he is seen as the number one ranked full-back of the four nations.
It should be noted that Fitzgerald will be making his first appearance on a rugby field for the first time in 36 weeks.
The man once touted as the likely successor to O'Driscoll in Ireland's outside centre slot has been bewitched by a serious neck/shoulder injury and an unfortunate saga over the negotiations about his combined Ireland-Leinster salary.
While Fitzgerald was playing the waiting game on the Irish Rugby Football Union's meagre contract offer - this involved a reputed cut in overall earnings from ¤280,000 to ¤200,000 - he was met with an injury serious enough to leave him on a Leinster-only contract for this season.
He has so much to prove to the IRFU, to Ireland coach Declan Kidney and to any potential suitors who would be interested in one of the most talented players in Europe.
The combination of the loss of all three world-class operators damaged Leinster almost beyond repair. It will take a miracle to make the European Cup quarter-finals.
Leinster are fast running out of matches and these three players are fast losing the time to recover their best form for The Scarlets and Exeter Chiefs.
It will all start in Edinburgh tomorrow night.