On days like this you could almost believe in the AIB League. Given the shopping centres were bursting on the last Saturday before Christmas a relatively large and vibrant 3,000 crowd - buttressed by a Shannon train load - were treated to something of a cracker.

Sure, for sheer quality there were too many errors and some of the defending shared the spirit of goodwill too much for the coaches' liking. When Shannon's Eddie Halvey and Conor Burke waved Alan McGowan through a narrow blindside corridor against the run of play the two sets of supporters would have been entitled to ask "are you Shannon in disguise?"

With the rusty champions, like Blackrock, willing to play a wider game than would have been within their compass a few years ago, it made for a fairly free-flowing and fluctuating game in which the lead changed hands three times and there was never more than a score between them.

Shannon's pack rumbled more effectively, occasionally steamrolled the Blackrock scrum and also held sway in the line-outs, where the pre-match loss of Leo Cullen reduced Blackrock's options further for Shannon to exploit through the peerless Halvey.

"They're up for it today," warned Halvey beforehand and there was also a discernible return of the old Shannon passion and desire.

Galwey, angered by a whack on the neck, launched himself at the blue and white hoops with ball in hand to inspirational effect, and Mark McDermott, back on his old stomping ground, was also fired up.

Then they had McMahon, at open side. He is reputedly the quickest player over 30 metres in Munster who may be accommodated in the centre or even on the wing by Shannon one day.

If there was a turning point it came with Brian Carey's missed penalty to touch in the 38th minute. Brian Roche counter-attacked, good ruck ball followed and McMahon surged onto Burke's well-disguised short pass through the Blackrock line from halfway before showing a clean pair of heels to both Carey and Aidan Guinan.

That was unfortunate on Carey, whose running, counter-attacking and tackling had made him look a class act before he injured his shoulder in trying to catch McMahon. Even so, while Shannon continued to have more of the ball, Blackrock's defence was better and so they seemed to have more of the chances, with Ryan Wheeler and Duncan Kennedy marauding influences despite their tight five's travails in the set-pieces. Few have ever made the yardage Wheeler did against the Shannon back-row.

In the first half, Eddie Robinson had been adjudged to make a double movement after a last-ditch flying tackle by Halvey while McGowan also dropped the ball after beating Burke once more with the line again at his mercy.

But the threat, especially out wide, remained and when Roche's inability to use his right foot led to a turnover, Blackrock moved the ball across the pitch to give Nicky Assaf a run and Robinson followed up to pick up and score in the corner.

Untypically, Shannon thus needed two attempts to close out the game. But after Andrew Thompson had kicked them back into the lead - his perfect six from six compared to McGowan's five from seven - they made no mistake the second time.

Kevin West, Blackrock's Kiwi coach, was encouraged by the "bravery and confidence" his team showed in "trying to play with the ball in the hand" against Shannon. "Perhaps we didn't believe we could win, like Shannon believed, which is something we're still getting towards. But, while we're disappointed not to have got six points, we're still delighted to have four points."

It still wasn't a vintage Shannon performance and the old air of invincibility seems to have gone, but coach Pat Murray countered by saying: "That may be so but I would argue if you give me my team back in August and two or three months of training together then you might have a different story. You could see that Blackrock were a team that had played together longer."

Undoubtedly, Shannon's best is still to come and a January based exclusively in Limerick, with a trip to Young Munster sandwiched by home games against Buccaneers, Lansdowne, Terenure and Garryowen, should reveal their true colours.

A snag here is that the IRFU have made such a dog's dinner of Thomond Park, with organic manure being laid on the sodden surface as recently as last week, that some or all might not be played at the ground where they have been invincible for four years.

Untypical of Shannon too was the near two-to-one penalty count against them and the lack of discipline which saw Alan Quinlan sent off deep into injury time after a wild substitute's cameo in his first game for seven weeks.

Publicly, at any rate, Murray wouldn't judge Quinlan and there were mitigating factors. The injury-time punch to Guinan followed the perceived stamping of Foley and the Blackrock winger apologised to Quinlan outside the dressing-room afterwards.

Scoring sequence: 7 mins: McGowan try and con, 7-0; 15: Thompson pen, 7-3; 20: McGowan pen, 10-3; 26: Horan try, Thompson con, 10-10; 33: McGowan pen, 13-10; 38: McMahon try, Thompson con, 13-17; 42: Thompson pen, 13-20; 47: Robinson try, 18-20; 50: McGowan pen, 21-20; 57: Thompson pen, 2123; 70: Thompson pen, 21-26, 77: McGowan pen, 24-26.

Blackrock College: B Carey; A Guinan, E Robinson, M Roche, T Keating; A McGowan, A Boyd; P Flavin, S Byrne (capt), I McLoughlin, R Casey, H Kos, R Wheeler, R Summers, D Kennedy. Replacements: N Assaf for Carey (38 mins), P Jordan for McLaughlin (51 mins), J Ryan for Summers (68 mins).

Shannon: B Roche; A Thompson, A McGrath, R Ellison, Jason Hayes; C Burke, S Johnson; M Horan, M McDermott, John Hayes, M Galwey, D Kirby, C McMahon, A Foley (capt), E Halvey. Replacements: J Lacey for Roche (47 mins), A Quinlan for Kirby (51 mins).

Referee: R McDowell (Munster).