Despite having lock Jamie Cudmore sent off after just 18 minutes, Clermont led 13-11 with five minutes remaining.
Munster's title defence appeared to be in severe doubt before two tries in the closing stages turned the game around to keep the Red Army in pole position for quarter-final qualification.
The double European Champions may have survived with a win that day but the match dismissed any thoughts that French sides would be beaten before even arriving at Fortress Thomond.
And having seen first-hand how close Clermont came to lowering his side's colours on Munster's own hallowed turf, Lions leader O'Connell won't be taking Perpignan lightly come Friday evening.
"Clermont showed up with all guns blazing when we played them here last year and we were lucky to get away with a win," said O'Connell, who toured New Zealand with the Lions four years ago before leading Ian McGeechan's tourists into battle this summer.
"The final is on in Paris this year. Perpignan are the French champions. They're a real strong force in French rugby I've no doubt they'll be here with a strong team on Friday night. They've everything to play for.
"Last time we played them we played an unbelievably tough game in the quarter final in Lansdowne Road (in 2005/06) and barely won. So it's going to be a very tough game and I've no doubt they'll field a very strong side."
O'Connell is acutely aware of Perpignan's strengths, particularly as they seem to mirror those most closely associated with Munster's own biggest weapons.
The Ireland and Lions second row knows that Friday's battle will be won and lost up front and that there will no place for shying away from close-quarter contact.
Munster's talisman is expecting a hugely physical encounter, they type where no hiding place can be found and where men will be separated from boys. Fortunately for the Munster faithful, it's exactly the kind of environment in which O'Connell excels.
"Obviously they're a massive scrummaging side. The scrum is very big for them," added O'Connell.
"They're a very big mauling side. They maul most of the ball they get and they're very good at it. It's going tot be a very tough challenge.
"They kick a lot from their own half of the pitch but when they get into your half, they're a typical French side play with a lot pace, play with a lot of width.
"They're a bit like Clermont in that they challenge you both ways. They take you on hard up front at scrum and maul and then when they're in your half they like to go wide and have a very good backline to do that. It'll be very similar to the Clermont game here last year in that they'll aim to take us on both ways."