Now the talismanic second-row hopes to be involved in Sunday's crunch match, the first of two games with the star-studded Welsh region
"It was great to get back last weekend," said O'Connell. "I played 40 minutes the week before for Young Munster so I knew the body was up for it.
"It's great to get back and play for Munster at last and I just have to work on match fitness and sharpness.
"It would be great to play some part in Sunday's game. The team isn't named yet, so we don't know, but I'm hoping to be involved.
"It would be brilliant to get back involved in Heineken Cup action, I haven't been involved in Europe since last January.
"But it's also important that I'm patient. We have an incredible number of high-class second-rows in the squad.
"There's massive strength in depth in that position and it's important that I get up to the level they're at before I can be considered for selection."
After losing to London Irish in the first round of European action, before beating RC Toulon at Thomond Park, O'Connell is all too aware of the magnitude of the double-header with the Ospreys.
"These back to back games with the Ospreys are going to be really tough - two big games which will decide if we're still in the group come January," continued O'Connell
"When you lose your first game in Europe you realise every game from then on can rule you out of the competition, your back's to the wall.
"You can sense that with the lads this week, it's a very tough two weeks but we were in the same situation last year against Perpignan.
"After a poor performance in the first week we did well in the second game. So if we can get a win this week by any margin at all it will be great."
The Ospreys have been hit by a double blow in the build-up to the games after both Marty Holah and Lee Byrne were ruled out. But O'Connell reckons they still have plenty of quality.
"They've an incredible staff of players, New Zealand internationals, Lions, Welsh internationals and Scottish internationals. They've a phenomenal squad and one of the biggest budgets in Europe.
"They're a really big challenge for us back to back. We've beat them this year but we lost twice to them last year in the Magners League, which they went on to win by beating Leinster away from home.
"They're an excellent side and are a lot more experienced than when we played them in the Heineken Cup a couple of seasons ago. It's going to be very tough."