It could be called the match they can't call.

Some bookmakers are struggling to split the teams and the analysts convey very little conviction if indeed they do come down on one side or the other.

It's Leinster, defending and four-time champions, versus Saracens, winners from the previous two years.

The Blues, under Leo Cullen, the only man to have won the competition as a player and a coach, have just one European defeat to their name over the last two seasons, that a one-point reverse in Toulouse last October. And even that was due to an uncharacteristic lapse that led to an intercept.

Among the victims of the 2017/18 clean sweep were Sarries, minus Billy Vunipola, unable to live with Leinster's pack in the quarter-final in Dublin.

The big man is back this time, however, and so is his brother Mako, cleared following an ankle injury earlier this week.

"We were in a different place then," said Saracens boss Mark McCall, a former Ireland centre.

"England had just had a very poor Six Nations and Ireland had just won the Grand Slam

'We were missing some key players and it just feels different. That doesn't mean we will win but we will be in a much better state mentally going into that than we were 12 months ago."

There is a sense that Leinster, who have beaten Saracens in their three previous meetings, have not reached the levels of last season, that there is still room for improvement.

Without that lift in performance, Leinster will leave St James' Park, another first-time venue for the tournament final, without their crown.

The champions were magnificent last season, with six wins from six in the pool, comprehensive wins over Sarries and Scarlets in the knock-out stage and a gritty character-revealing triumph in the final over Racing 92.

It was always going to be hard to follow a season, which also brought a Pro14 title, with the same level of intensity, the same desire.

Speaking before a scrum was set this season Tadhg Furlong spoke of attacking the title, not defending it. That will have to come into evidence more so than even on Saturday.

Leinster beat Saracens in last year's quarter-final in Dublin

Leinster also beat Bath and Wasps in the pool stages home and away but the nature of the win over Ulster was a concern for Cullen and his side.

The semi-final against Toulouse in Dublin was impressive but the French attitude on that day has to be taken into account.

"I'm still trying to weigh up if Toulouse didn't really play their best game today or if we didn't let them do it," pondered Rob Kearney.

The full-back was also asked how he thought the class of 2019, who don't have Jordi Murphy, Dan Leavy, Josh van der Flier or Isa Nacewa at their disposal, compare to 2018?

"I'd like to think we've got a little bit more squad depth," he replied without volunteering any names that could match that missing star power.

What they do have is one James Lowe, the powerhouse Kiwi winger who adds an extra dimension to their game.

Saracens flanker Mike Rhodes admitted to RTE Sport that their tactic of kicking the leather off the ball during the win over Munster in the semi-final came about in part due to the lack of experience in their back three.

While Jordan Larmour is unproven as an aerial defender, Kearney and Lowe can be relied upon and more.

Still, McCall's men, who provided six of the England team that kicked Ireland off the park in February, would be wise not to abandon this aspect of their game plan on that basis alone.

Robbie Henshaw says the team have learnt lessons from Saracens' semi-final win, their eight victory in a row in the competition.

"Physicality stands out," said the centre. "Looking at their game against Munster, it was dog eat dog.

"We need to be ready for what's to come, they went after Munster in the air. We need to be incredibly clinical and we need to be physical."

The English champions are second in the Premiership, long since guaranteed a home semi-final in the play-offs, and warmed up for this game by resting their front-line players against table-toppers Exeter, who also fielded a second-string team.

Sarries won 38-7.

There are key battles all over the park but the prospect of James Ryan, the Ireland player of the year shoo-in, taking on Maro Itoje is the one to savour.

Maro Itoje was a central figure in Saracens' semi-final destruction of Munster

The 22-year-old lock seems incapable of a poor performance. If Leinster win, he'll have edged the battle with the Lions forward.

Similarly mouth-watering contests between Johnny Sexton and Owen Farrell, Furlong and Mako, Liam Williams and Lowe are on the cards too and if this is not a closely fought game then nobody will have read the script correctly.

So often this matches come down to the "small moments" says McCall. "It might be a magical moment, it might be a switch-off moment."

But it's hard to find fault with Eddie O'Sullivan's assertion from the RTE Rugby podcast.

"My one concern for Leinster is that this is a bit of a mission for Saracens," said the former Ireland boss, "they feel that this is their year to come back and make a statement."

It's up to Leinster to make a statement off their own: that they have no intention of handing over their crown just yet.

Let the battle commence.

Verdict: Saracens