Van der Flier form tackles the problem of injury issues
It would seem the hip hiccup that caused Sean O'Brien to miss the interprovincial derbies against Munster and Connacht will strike again against Ulster at the RDS this Saturday (KO 5.35, TG4 & Sky Sports).
In fact, there is no certainty the British & Irish Lions test flanker will make it back for the Glasgow Warriors in the fifth round of the Champions Cup at the same venue on Sunday week.
You see, O'Brien was touch-and-go for Exeter Chiefs in the second leg of their Christmas back-to-back matches in Europe.
The next man up to play against the Ulstermen would have to be Dan Leavy, based on his Man-of-the-Match impact against Munster.
However, the openside is a doubt for Saturday with a back injury, not thought to be serious, that could rule him out for the last of the three interprovincials.
"He is a special player," noted Leinster assistant coach John Fogarty, about the impact of Leavy.
"He always had an x-factor about his game. He has improved in areas of the game where he needed to.
"He's a very physical player. He carries with a low centre of gravity and is very heavy in contact.
"On the other side of the ball, he puts himself in strong situations to get over the ball and get some rewards.
"He is a very talented player who gets a lot of big moments in the game.
"But we want to see him put together 80 minutes performances, staying robust, staying fit and offering for the team across all parts, not just the big parts."
The sense of unease has been diminished by Josh van der Flier's astonishing tackle output against Connacht on Monday.
The Ireland flanker set a record PRO14 League mark of 34 tackles, with none missed.
The machine-like efficiency of Van der Flier's work is his calling card for a player rightly lauded for his application, on and off the field.
The interprovincials are starting to take a toll, even on Leinster's depth chart.
Centre Rory O'Loughlin (concussion), hooker Richardt Strauss (back) and second-row James Ryan (ankle) have all been ruled out for Ulster.
On a more positive note, Joey Carbery is scheduled to return to training this week, although he is weeks away from playing. The versatile playmaker could come into the Six Nations equation as long as he can get back in before the end of the month.
Loose-head Jack McGrath has come through his return-to-play protocols and scrum-half Luke McGrath passed his Head Injury Assessment on Monday.
Right wing Adam Byrne has recovered from a knee problem to add another option to the back three, where James Lowe and Jordan Larmour have been making their mark of late.