Victor Costello: 'Picking Leavy at No 8 was a poor decision and it must be rectified for Aviva clash'
It wasn't until after the first 20 minutes of the game in the Rec last Saturday evening when you could sit back and contemplate what was going to happen next because it was all just so unpredictable.
There were phases of play that we are not used to seeing with Leinster recently.
Bath attacked with a very strong lineout and scrum, which you would expect, but in open play, the visitors were well on the back foot.
The immediate reaction could be that this was going to be a long day as Bath halted Leinster in every facet of play and they carried hard into the defence
Luckily for Leo Cullen's men, Bath did not find or create many gaps but they managed to curtail Leinster and made them look like a travelling side stumped by the home crowd.
The back-row balance did not work and this had a detrimental effect on the overall performance, and they got out of jail in a very important away game.
In recent times Leinster have been able to sit back and absorb the pressure, but this was different.
Bath were much better than their Premiership results and performances have shown and when a team absorbs this much pressure their weakest link, if they have one, cracks.
In this case it was the back-row and the breakdown. The selection of Dan Leavy at No 8 was a bold one and the modern thinking in this area is that the number on your back should not matter in the back-row.
Leavy is a certain starter when fit and available but this selection was a bad move.
Leinster were slow to the breakdown with Leavy not on the flanks and communication between him and Luke McGrath was non-existent.
Rhys Ruddock should have switched immediately as Leavy struggled to be his most effective self and this is the second time in this competition where selection error has either cost Leinster the game or a performance.
Ironically, the back-row is the most abundant of all of Leinster's units.
This selection was trying to be too smart and gave Bath a focus before kick-off.
The Premiership is not what it used to be and with the constant integration of foreign players, the competition has suffered.
But the English DNA is quite regimented. They will do the simple things well: scrums, lineouts and the breakdown will be marshalled and those players given the task in these positions will execute their primary role.
Anything else on phase or open play will be down to individual flair or talent. Leinster played into Bath's hands and were not thinking clearly on the pitch.
When this is happening, calls need to be communicated to the players from the management, or changes made.
Johnny Sexton, who is always a target, took a hit early on and yet battled on to the final 20 minutes, but he was on his own in the leadership department and as a result this was a more attritional game than it should have been.
As you would expect, Leinster never gave up.
The pack and ball-carriers have full faith that if they stick to their job, no matter what the score or environment is, the outcome will be a victory.
This was true; Ruddock, Tadhg Furlong and Cian Healy's hard mileage for Leinster must be in the thousands at this stage with James Ryan catching up rapidly.
The work-rate of the pack kept them in the game and when the opportunity came Leinster took it.
Yes, it was lucky and came off a poor Leinster throw in the lineout but Cullen's side are mature enough to take their chances when they see them.
Jordan Larmour was never going to get caught.
His ability and talent make him an extremely exciting player but this excitement gets him caught out defensively and he will become a target should he not gain some structure.
Unlike travelling French sides, Bath will come to the Aviva for a second bite of the cherry.
They will have the same game-plan to slow down the ball and they will probably sharpen their kicking game.
Leinster's performances in Europe this season have not matched their favourites' tag so they need to play in a manner of achieving maximum points.
With Bath effectively out of the competition, this is always a dangerous position to be in. Playing at home in Europe, you're always expected to win.
There is no doubt that the Leinster management will be trawling through the footage of last week's game to correct plays that didn't work,
They will have to look at their lineouts and the protection of the ball at the breakdown.
Jack Conan immediately balanced the back-row and used the Leinster scrum as the solid platform it is to set up quick ball for the backline.
Ross Byrne continued his international form by having the vision and confidence to swing a wide ball to an underutilised James Lowe who launched a kick into open space to kill off any further threat from Bath.
For Leinster, the last 20 minutes of the last game needs to be the standard for tomorrow.