This was the Ospreys' fourth game in fourteen days and they had picked up a few injuries in the face of such a high workload, but wins over the Dragons and Scarlets were only marred by their defeat by the Cardiff Blues before Christmas.
There were ten changes from the side who doused the Dragons' flames 12-6 on New Year's Eve and ten of the side at Donnybrook were on the weakened Ospreys side which beat Australia while their stars were absent on Wales duty.
One of the heroes that day, Shaun Connor, switched the kick-off to the right hand-side away from his forwards. The tactic paid off as his pack put the hosts under some early pressure before Connor stroked over a fifth-minute penalty.
Contepomi replied for the hosts shortly after, but Ospreys' right wing Richard Mustoe danced his way around several would-be tacklers before his flip pass was gathered up by lock Brent Cockbain.
Leinster went on the attack first: Contepomi was only a forward pass away from a superb individual try after his break with scrum half Chris Whitaker. Fullback Rob Kierney then ran back a clearance kick from Connor to cross for the try which put his side level.
Contepomi slotted the conversion to put the hosts ahead before Gordon D'Arcy darted through a gaping hole in the defence to put Brian O'Driscoll over. Another Contepomi conversion made it 17-8 at the break.
The Ospreys were down to fourteen men after the break when No.8 Andy Lloyd was shown a yellow card for killing the ball at the base of a ruck near his own line. In his absence, Leinster wing Dennis Hickie went over in the corner as the hosts cruised out to 24-8.
The bonus point arrived after fifty-two minutes when a wrap-around from O'Driscoll put Kearney over for his second try and his side's fourth. O'Driscoll grabbed one for himself when he skipped past several defenders and brushed off tackles on his way to a superb try.
The Ospreys' fightback started when replacement scrum half Jason Spice made a break and Stefan Terblanche strolled over near the posts. Connor landed the conversion to pull the scores back to 38-15.
A ball from the top of the line-out to Spice saw Lee Beach put fellow flanker Richie Pugh over for his side's third try to make it 38-22 with ten minutes left. Yet when flanker Keith Gleeson went over with time running out for a converted try, the Ospreys had been soundly beaten.