URC: Cardiff 8 Leinster 7

Harry Byrne’s first taste of action in over a month lasted only three minutes as Leinster’s 11-match unbeaten run ended at the Cardiff Arms Park and, with it, the chance to reach the URC summit.

Released from the Ireland squad having not featuring in the opening three rounds of the Six Nations, 26-year-old Byrne slipped off a tackle with the game still in its infancy.

He took a knock to the face in the process and didn’t return from a head injury assessment, making the outhalf a major doubt for Ireland’s encounter with Wales on Friday. Charlie Tector replaced him off the bench.

Robbie Henshaw and Jimmy O’Brien, who made their comebacks from injury, could now come back into frame for Andy Farrell.

However, for Leo Cullen and Jacques Nienaber there was disappointment as the arrival of Leinster’s mini-bomb squad before the break failed to change the course of the game, with Cardiff handling the difficult conditions better.

It was cold and wet in the Welsh capital, but emotions ran hot in the first minute when Leinster novice Alan Spicer and George Nott clashed off the ball.

Max Deegan, Leinster’s captain on the occasion of his 150th cap, was penalised by referee Sam Grove-White for being the next man in as a melee developed.

The conditions made the contest a lottery. Players on both sides struggled to hold on to possession, forcing a series of scrums and stoppages that killed any sense of momentum.

Leinster's Fintan Gunne is tackled by Cardiff's Taine Basham. Photograph: Andrew Dowling/InphoLeinster’s Fintan Gunne is tackled by Cardiff’s Taine Basham. Photograph: Andrew Dowling/Inpho

Cardiff led 3-0 at the break after Callum Sheedy slotted a close-range penalty.

For the most part it was chaotic stuff, signposted by Cam Winnett’s early kick-through that Ruben Moloney failed to gather. Leinster scrambled to survive, as they did on a couple of other occasions.

Byrne’s exit presented Tector with another chance in the pivot role, but he was instantly under pressure when he had a clearance blocked down. Worse, he was sent to the sinbin in the 13th minute for a late, no-arms tackle on Ben Thomas.

The 23-year-old, who had his first start at 10 in Leinster’s last outing against Edinburgh, returned to play after a bunker review.

At that point, the visitors were behind on the scoreboard when O’Brien knocked on and Thomas kicked through as Tector arrived, his act of foul play earning him the yellow card.

The home side turned the screw, with Sheedy’s superb 50-22 forcing Leinster on the back foot and, with James Culhane going off his feet at the ruck, the Cardiff outhalf made no mistake off the tee in the 19th minute.

Leinster’s best move of the half came when they were reduced to 14 men. Reiko Ioane’s charge up the middle and inside pass to Scott Penny opened a gap, the visitors shifted it wide via O’Brien and Moloney just ran out of space.

The hosts turned down another facile three-pointer 15 minutes from the break after Leinster were offside defending inside their 22. But the gamble failed to pay off as Dan Thomas knocked on at the ruck.

Leinster's Ruben Moloney is tackled by Cardiff's Callum Sheedy. Photograph: Andrew Dowling/InphoLeinster’s Ruben Moloney is tackled by Cardiff’s Callum Sheedy. Photograph: Andrew Dowling/Inpho

Cullen changed out his frontrow and half of the engine room in the 37th minute, with Rabah Slimani and RG Snyman coming on to add beef at scrum-time and experience around the pitch, but Cardiff struck the fatal blow 14 minutes into the second half.

Leinster cleared their lines into the opposition half but the counter was devastating. Winnett gathered possession, stepped Tector, and fed Grady on the left flank.

The winger took off before passing inside to Thomas, who fed scrumhalf Aled Davies for the game’s opening try. Sheedy missed the conversion attempt but, crucially, Cardiff had a two-score lead.

Leinster lost Joshua Kenny to injury soon after but were presented with a way back into the game on 66 minutes when Jacob Beetham reached one-handed for a 15-metre pass by Snyman to Moloney, and was pinged for a deliberate knock-on.

The Cardiff winger was sinbinned and the visitors were back in business just two minutes later when Henshaw’s inside pass released Kenny’s replacement Andrew Osborne and his assist sent newly-arrived Luke McGrath under the posts.

Tector converted and, with over 10 minutes to play, it was a one-point game. However, that was as good as it got for the province, who couldn’t find a winning score.

Cardiff dug in well to control the closing stages, with the victory moving them up to third in the URC table on 40 points, one point off Leinster.

SCORING SEQUENCE – 19 MINS: Sheedy pen 3-0; Half-time 3-0; 54: Davies try 8-0; 68: McGrath try, Tector con 8-7

CARDIFF: C Winnett; J Beetham, H Millard, B Thomas, M Grady; C Sheedy, A Davies; R Barratt, L Belcher, J Sebastian; J McNally, G Nott; A Lawrence, D Thomas, T Basham. Replacements: D Southworth for Barratt (57 mins), K Assiratti for Sebastian, D Hughes for Belcher (both 62), J Mulder for Davies (66), R Thornton for Nott (69), I Lloyd for Sheedy (72).

Yellow card: Beetham (66 mins).

LEINSTER: J O’Brien; JJ Kenny, R Ioane, R Henshaw, R Moloney; H Byrne, F Gunne; J Cahir, J McKee, A Sparrow; A Spicer, B Deeny; M Deegan, S Penny, J Culhane. Replacements: C Tector for Byrne (4 mins), A Usanov for Cahir, R Slimani for Sparrowm, RG snyman for Spicer (all 37), G McCarthy for McKee (37-75), L McGrath for Gunne (52), A Osborne for Kenny (57).

Yellow card: Tector (13 mins).

Referee: S Grove-White (SRU).