And having lost out 17-12 on that occasion, and 19-15 when the two teams met in Swansea earlier this term, stand-in skipper Shane Jennings is expecting another massive battle at the RDS.
"If we take our eye off Ospreys, they will do a job on us," said Jennings, who led Leinster in last weekend's win over Connacht in the absence of Leo Cullen.
"The last time they came over here, they won the League, so it is something to look forward to.
"The Ospreys did a job on us over there a few weeks ago. We're up for a big, big game. They have a very good team, a very good squad.
"Whatever lads come over we know we are in for a tough game. Every game for us is big because we are fighting to get into those top four positions."
Leinster have surged into the Play-Off positions after six wins and a draw in their last eight Magners League matches as they look to go one better than last season's Grand Final showing.
Having started the season slowly, Leinster now sit pretty in third place in the standings after hitting form from October onwards.
But while results may be pleasing for Joe Schmidt and his men, Jennings insists there will be no sense of complacency against the Ospreys after being made to work hard for their win over Connacht.
"We are pretty level-headed," added Jennings.
"As a group of players, I don't think we are too happy with the way we played for most of the game (against Connacht).
"There are a lot of frustrated heads, me included. We didn't control the ball at all. We didn't look after it at the ruck. We got clear instructions from the ref and we didn't deal with it properly.
"I don't think the score-line showed the way the game was. They certainly had us under a lot of pressure and we were very, very rusty.
"We regrouped at half-time. We realised if we concentrated on the basics, if we got a bit of shape, if we got a bit of ball, we could do a bit of damage."
"We have momentum. We have to concentrate on next week. We have to keep the ball rolling."
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