Principality Cup quarter-final Cardiff (3) 20 Tries: J Robinson, M Williams, R Williams. Con: Harris. Pen: Harris. Pontypridd (8) 18 Tries: Baber, Owen. Con: Davey. Pens: N Jenkins 2. Att: 6,000

A full-blooded first half full of niggle, foul play and fighting gave way to a skillful, thrillling match as the Blue and Blacks came from behind with three second-half tries to stun their visitors.

First Jamie Robinson made the most of a Ponty fumble to score, then skipper Martyn Williams and namesake full-back Rhys finished off flowing Cardiff moves.

Pontypridd produced plenty of thrills of their own and had two try claims turned down when they might have got the decision, but bow out at the quarter-final stage.

Pontypridd, with the wind at their backs, started the brighter and soon had Cardiff pinned in their own 22.

The home side managed to repel a rolling maul after a good Ponty lineout, then the visitors wasted a golden opportunity from a scrum in front of the posts when Duncan Bell was penalised.

Cardiff hooker Peter Rogers came off worse in an early tussle

England tourist Bell is set to join Bath at the end of the season, when Wales will implement five regional sides for cross-border competition.

Ponty believed they had a ready-made replacement at tighthead in Ben Evans, who had trained at Sardis Road after being released by Swansea.

But the Wales prop's U-turn to join Cardiff this week, ironically making his debut against Ponty in this match, added further spice to what is always a full-blooded clash of rivals.

Cardiff lifted the siege with the help of Iestyn Harris' boot, which then converted a penalty chance after 10 minutes.

The match was just waiting for a flashpoint, however, and Emyr Lewis duly obliged with a high tackle on Cardiff's Wales full-back Rhys Williams.

It was very hard to see where all the yellow cards came from Cardiff coach Dai Young

Peter Rogers attempted to extract some retribution, but was too engrossed with the prone Ponty wing to notice a fist flying towards his face.

Off to the blood bin he went, with Greg Woods a temporary replacement at hooker, while Ponty flanker Nick Kelly also needed stitches after the fracas.

The next two players to leave the pitch were opposing locks John Tait and Brett Cockbain, but their destination was the sin-bin as referee Hugh Watkins made a stand against the outbreak of fisticuffs.

Five minutes before the break the commitment was at last channelled into the rugby as Pontypridd put together a brilliant attack, ending with Gareth Baber scoring.

Jon Bryant and Lewis were both involved in text-book examples of releasing the ball from the tackle, leaving their scrum-half to dive over in the left-hand corner.

Pontypridd's Sonny Parker is tackled by Pieter Muller

Neil Jenkins had missed an earlier penalty and fared no better with the conversion, but made no mistake with a penalty in front of the posts deep into first-half injury time.

That came from Cardiff skipper Martyn Williams killing the ball at a ruck and getting sin-binned for his trouble, joining home prop Ken Fourie who had only just seen yellow for dragging down a scrum.

Two men light, the Blue and Blacks faced a torrid opening to the second half as Ponty looked to make the most of their temporary numerical advantage.

Yet Cardiff defended magnificently, with Pieter Muller to the fore, limiting Ponty to a single Jenkins penalty.

Then from the restart Cardiff stunned their visitors as Lewis spilled Harris' kick into the arms of Robin Sowden-Taylor.

The young blindside held his pass until the perfect moment before firing it wide to Robinson on the outside, the centre scorching over on the right.

You can't have players sitting by me when they should be on the pitch Pontypridd coach Lynn Howells

Harris missed the conversion but Cardiff were back in the match at 8-11 and growing in confidence.

Further evidence that the tide was turning came when Bryant was sin-binned for a deliberate knock-on as Cardiff threatened.

Cardiff, now back to full strength, needed no second bidding to take advantage and sent Martyn Williams over on the overlap for an unconverted try.

Pontypridd were stung into action and Lewis hit a great angle to burst through into the home 22, off-loading to Cockbain in support.

But the Australian lock was stopped in his tracks by Nick Walne, driven back by the Cardiff wing and conceded a penalty as he held on.

Cardiff full-back Rhys Williams is high-tackled by Emyr Lewis

With Ponty expecting a clearing kick, Ryan Powell took the tap and surged upfield, Robinson linking and Rhys Williams taking it the rest of the way to the posts for a seven-pointer.

Lynn Howells' men came roaring back and first Gethin Jenkins and then Michael Owen looked to have scored only for the referees' decision to go against them.

But Owen - who along with Mefin Davies was Ponty's outstanding forward - was not to be denied and forced his way over for a try that Brett Davey, handed the kicking duties, converted.

Trailing 20-18 defending champions Ponty now had five minutes left to keep their Cup hopes alive, as Howells replaced Jenkins with Ceri Sweeney at fly-half.

Cardiff were at full stretch but Pontypridd needed more composure and wasted several promising positions.

Ponty had one last chance with a difficult penalty kick from the halfway line, but Davey's attempt sailed wide to Cardiff's relief.

Cardiff: R Williams; N Walne, J Robinson, P Muller, C Morgan; I Harris, R Powell; K Fourie, P Rogers, B Evans, H Senekal, J Tait, R Sowden-Taylor, E Lewis, M Williams (capt).
Reps: J Yapp, G Woods, L Tait, J, Brownrigg, R Smith, N Robinson, M Allen.

Pontypridd: B Davey; G Wyatt, S Parker, J Bryant, E Lewis; N Jenkins, G Baber; G Jenkins, M Davies (capt), D Bell, B Cockbain, R Sidoli, N Kelly, M Owen, R Parks.
Reps: C. Thomas, C Sweeney, S James, M Rees, S Cronk, G Lewis, W O'Connor.

Referee: Hugh Watkins (Birchgrove).