Leinster were in sparkling form last weekend when they comfortably saw off fellow RaboDirect PRO12 side Ulster 42-14 to claim their third Heineken Cup in four years.
Try-scorers Sean O'Brien and Cian Healy, along with Ireland centre Brian O'Driscoll, looked in formidable form and after ending the regular season top of the table Leinster look sure to start the final as favourites.
The Irish province will also enjoy the benefit of playing on their own patch at the RDS but Howley, the former Cardiff and Wasps scrum-half, insists Ospreys can upset the odds.
"The Ospreys have a great opportunity and I think they will win the match," he said.
"I can only liken it to when I was a player when it is difficult to lift yourself after a major victory.
"I remember when I played for Wasps in the 2004 Heineken Cup final, we had Bath in the Premiership play-off final six days later.
"It was tough and we did not train until the Wednesday or Thursday and only had two sessions.
"It will be crucial how Leinster prepare. But, psychologically, when you become European champions, it's difficult to go out to try and play a game which is your regional equivalent.
"The Ospreys will have had two weeks rest and I am sure they will take a lot of confidence going into Sunday, having put together an impressive run of results.
"It would be a huge boost to the Welsh camp if they won."
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