Nick Evans can give Harlequins a slight edge against Leinster at The Stoop

Form, as a noun, is the visible shape or configuration of something. It’s a particular way in which a thing exists or, and this is crucial, appears.

A more accurate categorisation of Leinster’s “form” should follow after Sunday.

“How do you guys categorise form?” asked Matt O’Connor on Thursday. “Is it winning games, is it scoring tries? We’ve scored the most tries (25) the league.”

The 16 tries conceded is the worst of any team in the top six.

“I’m asking the question,” O’Connor continued. “What’s form to you guys? Because you ask about it a lot.”

Some smoke is visible above the forest. But no flames, not yet. Leinster’s form has been patchy at times this season but mostly solid – like their outhalf. They still possess that ability to raise their intensity along with the stakes, especially at home, especially in the last quarter of a game.

Four wins

Harlequins’ form too, despite two wins from two in Pool Two, is questionable after just four wins from nine Premiership outings.

Let’s start at the back. Rob Kearney’s influence against that of Mike Brown is a dead heat that gets three chances to be figured out between now and March 1st.

The wingers – Aseli Tikoirotuma and England's Marland Yarde against Darragh Fanning and Luke Fitzgerald – should provide fascinating viewing. Presuming Fitzgerald's body holds up, the Fijian will be tested in all aspects of wing craft while Fanning's form has benched Zane Kirchner. That's some compliment.

No reason why Ian Madigan and Gordon D’Arcy cannot hold sway in midfield.

What matters, as ever, is how the dice falls inside them. Jimmy Gopperth is a decent second-five-eight from New Zealand, Nick Evans is an All Black standard second-five-eight from New Zealand. Danny Care is a sharper, more dangerous scrumhalf than his opposite number.

Small margins

That should stack the small margins in Harlequins’ favour unless the

Leinster

backrow ruin Care’s ball. Denied the injured (in-form) Dominic Ryan, at least

Jordi Murphy

has settled back into the seven jersey. Nullifying the relentless

Chris Robshaw

, as Tommy O’Donnell did at The Stoop in 2013, is Murphy’s greatest challenge to date.

He has help. Rhys Ruddock and Jamie Heaslip are the form players in Ireland right now. They can win this game for Leinster.

Kane Douglas, following two concussions since October 31st, will presumably relieve Mike McCarthy at some juncture. His Wallaby brawn seems essential.

Mike Ross versus Joe Marler is like Kearney and Brown, Part One. Jerome Garces’ interpretation at the scrum might tilt the outcome.

"It will be physical," promised Harlequins director of rugby Conor O'Shea as he welcomes Robshaw, Care, Brown and Joe Marler back from a international duty.

“They are suffering a little bit...to play New Zealand, South Africa, Samoa, Australia all in a month is a tough gig!

“You can’t drop down a level. This is another Test match. Mentally it is good the England boys won against Australia, it helps.”

The idea is to kill off Leinster by Christmas. That hasn’t happened since 2012 and previous to that, in 2007.

O’Connor says he wants to play a running, ball in hand game but added: “Our philosophy is finding a competitive advantage against the opposition to win the game. That’s our style of rugby.”

Harlequins’ leadership group allied by Evans to shade it but Leinster can salvage a bonus point and dominate at the Aviva next Saturday. That would be acceptable form.