Leinster Rugby slipped to their first defeat of the Guinness PRO14 campaign with Connacht taking maximum points from the RDS Arena.

A late try from replacement Ed Byrne rescued a bonus point for the hosts but it came as they were 18 points in arrears.

The men from the west were quickly onto the front-foot, wing Peter Sullivan making inroads. The recycle was fluid for John Porch to test Andrew Smith’s outside shoulder and the Leinster debutant was up to the task.

It then took a double hit from James Tracy and Peter Dooley to shake the ball loose from Shane Delahunt five metres out.

The Leinster scrum was in the ascendency, powering up a penalty and a free-kick until Ross Molony’s pass was picked off by Jack Carty who raced in for the opening try from 40 metres out in the 10th minute.

There were good signs from Leinster’s other debutant Max O’Reilly on two counter-attacks, the second drawing a penalty from Caolin Blade’s high hit.

The home side were made to look for the ball in behind by the intensity of Connacht’s defence, Johnny Sexton, Rory O’Loughlin, O’Reilly and Luke McGrath all kicking for distance or position.

On halfway, hooker Tracy was whistled for not rolling away and Carty fired a touch-finder to within five metres. The Westerners opted to go to the back where Devin Toner stole the lineout and Jimmy O’Brien dispatched.

Soon after, Delahunt sniped the fringes and Blade was there to accelerate. Carty was up in support to test the vigilant O’Reilly. Tom Daly piled forward and Carty had the momentum to burst over to go a dozen points up in the 23rd minute.

However, the home forwards counter-rucked, Leavy pinched a turnover, McGrath popped the pass and Scott Penny flew to the posts for a try in their first meaningful attack.

Back-to-back turnovers by Leavy allowed O’Loughlin to pin Connacht back inside their 22 with a diagonal ball.

Penny was offside from a lineout to hand the initiative back to Carty who kicked another three points in the 32nd minute.

The speed of the chasing Porch prompted O’Brien to pass to O’Reilly, who was quickly pressured by Oliver and Gavin Thornbury for another penalty struck by Carty for 18-5 in the 36th minute.

A brilliant burst by Ryan Baird looked like eating into the lead, Tracy adding to the ground-made until Eoghan Masterson nabbed a penalty at the ruck.

Connacht were still pushing the pace, Daly snaring Liam Turner deep in defence to force an attacking scrum. From there, Blade scrambled to the posts and the ball was moved left for Alex Wootton to score in the corner for 25-5 at half-time.

Leinster had to strike back, and quickly, to get back into the game. They went straight to moving the ball at speed against Connacht’s preference to play for territory.

The Blues got what they wanted when a sweetly worked lineout was supported by punching carries that enabled McGrath to pick and fake the pass for a fine try which O’Brien converted.

Connacht’s response was to bundle Dave Kearney into touch and earn a penalty from a solid maul for Carty to connect for a further three points.

Replacements Seán Cronin, Jack Conan and Byrne were summoned for duty just before Molony’s lineout take put Leinster on the front-foot.

An immediate carry by Conan was met with stubborn resistance, Connacht hammering into the tackles.

Leinster were not about to be denied, Cronin bursting clear of a maul outside the 22 to find Baird on his left and the blindside made his way home.

The pressure was forcing issues, Denis Buckley taking his eye off the ball to concede a scrum on the 40-metre line.

Then, David Hawkshaw was the architect of a superb attack, the replacement knifing in between defenders, releasing O’Brien along the tramlines and taking the return pass for a stunning try. Or, so it seemed.

On review, the try was ruled out for obstruction by Smith on Sam Arnold and Connacht replaced the concession of five points with an attacking lineout.

It was frenetic action, Carty looking to turn the screw with his tactical kicking and Leinster going for broke from distance, Hawkshaw almost streaking clear and Baird looking dangerous in the wide channels.

Importantly, Connacht were edging the territory going into the last 10 minutes, Kearney’s awareness sniffing out the danger posed by a Carty grubber to the corner.

Leinster were undone by another intercept, Daly stepping up to grab the ball and the decisive try.

Leinster did what they could to repair the deficit with Byrne eventually driving to the line for a losing bonus-point right at the death.