Bernard Jackman believes the victor in Saturday's Heineken Champions Cup decider can rightfully claim to be "the best European team ever".

Holders Leinster take on Premiership heavyweights Saracens in a mouthwatering showdown at St James's Park in Newcastle. They've six European Cups between them (Leinster have four, Sarries have two) and Jackman says the weekend's arm wrestle will determine the true top dogs on the continent.

"I think it's going to be an unbelievable clash. I'm not trying to hype it up, but I think whoever wins this can probably say they're the best European team ever," he told RTÉ 2fm's Game On.

"If Leinster beat Saracens they've really proven themselves having gone back to back. It'd be a bigger achievement for me than beating Racing last year. And if Saracens beat Leinster they can say they beat the champions and bounced back from a quarter-final defeat last year. They've got some phenomenal players."

Saracens barged past Munster in the semi-finals, flexing their muscles in key moments to crush the province's hopes. Jackman said their strength in depth is frightening, but if anyone can stare them down, it's Leinster.

"I was so impressed in the semi-final with the bench Saracens brought on against Munster. On the 50-minute mark they're bringing on Will Skelton, Schalk Burger, Vincet Koch, Richard Wigglesworth, Alex Lewington. That's phenomenal. 

"What Munster weren't able to do was get off the line because Saracens kept on punching holes generally at that second defender, and once they got that forward momentum they came at you again and again. They never let you off the hook by throwing a long pass. I haven't seen any team execute that type of strategy as well this season as Saracens did. 

"When they get quick ball and they come at you, really flatten the gain line with short passes off nine, it's very difficult to stop them.

"Saracens won't have met a team as fit or as mentally strong as Leinster this year. That's going to be interesting, how they handle that. Leinster you'd imagine will thrive under those circumstances where they are really under the pump."

Jackman expects an almighty battle on Saturday. Sarries have so much in their arsenal - but Leinster are the champions for a reason. Ultimately, he predicts it will be Leo Cullen's men lifting the trophy above their heads. 

"I've gone full circle on this. After Saracens-Munster, I said 'wow, nobody is going to beat them'. That's how impressed I was with them.

"Leinster showed on the Sunday against Toulouse that they were heading back towards their best. They are the holders. They'll absolutely be ready, physically and mentally, to put a performance together on Sunday. I think it will just be enough."

Follow Leinster v Saracens (5pm) with our live blog on RTÉ.ie and the RTÉ News Now App or listen to live coverage on RTÉ Radio 1's Saturday Sport.