As well as claiming European club rugby's greatest prize in 2009, 2011 and 2012 and setting his side on their way to the Amlin Challenge Cup trophy before missing the final in 2013, O'Driscoll has won 126 caps for his country and tasted Grand Slam and Triple Crown glory.
The 34-year-old started two Tests on last summer's victorious Lions tour of Hong Kong and Australia in what was his fourth straight series for Britain and Ireland's elite and he was considered a modern-day great long before he announced his plans to retire at the end of the current campaign.
And now McFadden, who has been a senior clubmate of O'Driscoll's since 2007, reckons the former Leinster, Ireland and Lions skipper should be hailed as an even better sporting success story than the likes of footballer George Best, motor cyclist Joey Dunlop, jump jockey AP McCoy, snooker star Alex Higgins and rugby heroes Willie John McBride and Mike Gibson.
"In my opinion he's the greatest Irish sportsman of all time. Regardless of what he does this year, I think he is already at the top of the list for Irish sportsmen," said McFadden.
"We've got to cherish these last few months, big time. It's been amazing to play alongside someone of that level, and long may it continue for the rest of the season.
"I don't know what he's going to do next year; he keeps his cards pretty close to his chest with everyone, not just with the public. But it's been a pleasure, playing with him for both Leinster and Ireland. It would be great to have some silverware to back it up as well."
Leinster will hope that silverware arrives in the continent's biggest club competition next May as they look to equal Toulouse' record of four European crowns.
Matt O'Connor's men have begun their latest Heineken Cup quest in fine form, winning their opening two games to take control of Pool 1. Victory at the Ospreys was followed by a home win over French Champions Castres Olympique to leave Leinster with a three-point cushion over their next opponents, Northampton Saints.
Leinster travel to the East Midlands on Saturday, December 7, with the return fixture set for exactly a week later at the RDS. If, as expected, O'Driscoll starts both those fixtures having missed rounds one and two, he would move on to 84 European Rugby Cup appearances since making his Heineken Cup debut back in 1999.