Jimmy O’Brien’s four-try salvo was the highlight of Leinster Rugby’s 10-try win over Bath Rugby in the Heineken Champions Cup at The Rec.

It took Leo Cullen’s men some time to find a rhythm. When they did, they hummed like a prestige car.

Despite Bath’s position in the Premiership, they were keen to make an early impression, assisted by Leinster’s indiscipline.

Just when the Irish province looked like moving clear of pressure, Michael Ala’alatoa was slow to move at a ruck, inviting a second and third attacking lineout.

Stuart Hooper’s men were driven back in contact, a savage collective counter-ruck giving Leinster a scrum from which Jack Conan made ground.

Luke McGrath’s bomb edged the Blues upfield enabling Hugo Keenan to take the return kick back with interest.

A sustained attack, sparked by Caelan Doris’ burst, stressed Bath to breaking point, Jonathan Sexton’s grubber putting Max Clark in a bind.

The actions of Jordan Larmour, pulling Clark back, denied Jimmy O’Brien an opportunist try and this was compounded by Rónan Kelleher missing Josh Murphy at the lineout.

Leinster’s willingness to keep the ball alive, triggered by O’Brien’s rescue of an unclaimed ball, was fuelled by unorthodox passing and Larmour’s shakedown of the home defence.

It produced a scrum on the right, deep inside the 22, leading to an unfortunate head knock that removed Bath’s Sam Underhill from the fray.

Another scrum was used by Conan and Josh van der Flier to put Bath on their heels and Keenan’s pass execution put O’Brien over on the left for a try in the 16th minute.

Larmour and Andrew Porter were secure at the restart. But, the Blues were finding it difficult to escape their half, leading to a Bath scrum.

Their organised defence handled the pressure well and the eagerness to counter was just undone by rusty handling.

A power surge at the scrum was backed up by a smooth lineout throw by Kelleher, Sexton’s show-and-go splitting the line.

When that didn’t quite work out, Leinster were patient in their build-up to van der Flier’s exquisite line onto Sexton’s ball for the second try, the captain converting for 12-0 in the 26th minute.

An uncharacteristic spill by Doris caused a problem solved by a dominant scrum which led to a lightning strike for Keenan to slip Larmour through a narrow gap.

Once in behind, the Ireland wing shot past flat-footed defenders for a beautifully designed try, converted by Sexton.

Just as they were beginning to take over, a breakdown in play between Porter and Sexton allowed Charlie Ewels to pick off the pass.

When O’Brien got back to cut down Ewels, centre Clark was on hand to finish the job, Orlando Bailey’s conversion making it 19-7 in the 34th minute.

The response was ruthless. Sexton tickled an angled ball for O’Brien to score at his ease for the bonus-point.

Then, an accumulation of penalties placed Bath in a perilous position. The forwards ground out the yards for Ciarán Frawley, a blood replacement for Larmour, to squeeze out the fifth from another textbook line, Sexton’s conversion making it 33-7 at the break.

Max Deegan’s half-time introduction coincided with a dominant tackle and one-man counter ruck to put Leinster on the frontfoot.

Gabriel Hamer-Webb’s stray hand earned a yellow card and Leinster took advantage from Ryan Baird’s lineout take for Porter to stretch to the whitewash for another seven points.

A sweeping move, oiled by pinpoint passing, put Larmour close to another before Sexton smartly exploited a quick penalty to kick-pass over for O’Brien’s hat-trick.

A third try in four minutes arrived out of Sexton’s chip, O’Brien and Ringrose’s involvement, Henshaw’s offload and Keenan’s touchdown for 50-7 in the 53rd minute.

Bath scrum-half Ben Spencer’s cute move tempted Deegan into an off the ball obstruction for which the loose-forward was binned.

They were under the cosh, Keenan and O’Brien posting tremendous tackles on Ruaridh McConnochie and Hamer-Webb, respectively to keep Bath at bay.

Jamison Gibson-Park slipped a sweet ball to Dan Sheehan for the hooker to speed home, Ross Byrne slotting the extras for 57-7 in the 70th minute.

Bath were on the verge of scraping a consolation score when Conan snatched the ball out of a maul, headed off, kicked long and Gibson-Park was fresh enough to chase for field position.

Larmour latched onto a loose ball, hacking on, for O’Brien to win the race for possession for his fourth, converted by Byrne, on a day the Kildare man will never forget.