The 22-year-old No. 8 produced a number of impressive surges in a man-of-the-match performance as two late Jimmy Gopperth penalties guided the hosts to an 18-12 victory, their fifth GUINNESS PRO12 triumph this season.
Ian Madigan and Sam Davies landed three penalties apiece to make it 9-9 at the interval before Gopperth took over kicking duties when Madigan was forced off after turning his ankle.
The fly-half was unerring late on to ensure Leinster bounced back from a shock draw against Benetton Treviso last weekend and O'Connor highlighted Conan's contribution in spoiling the tactics of Steve Tandy's side.
"Jack Conan is getting better and better every time he plays," he said.
"I think he was hands down the man of the match tonight and he probably was last week against Treviso as well.
"It was tough. Ospreys came with a pretty good plan to get off the line and make it hard for us at the breakdown and play good field position.
"Full credit to them, they delivered that plan and got a point out of it.
"We created a couple of chances after the break and we probably put ourselves in a position to score two or three tries. For a couple of reasons we didn't take those and it left Ospreys in the game."
Click here for the best images from Leinster's hard-fought win against Ospreys
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