Cardiff, who got into the Heineken Cup only via a repêchage in Viadana, lost the first half 13-6 and looked in a bit of a mess. A rollocking at half-time - the coach Dai Young has grown accustomed to delivering sermons - resulted in his team scoring four tries and 34 points without reply in the second half. The Arms Park crowd, as subdued as their team before the interval, finally caught the celebratory mood as Cardiff got their campaign off to an encouraging start, complete with a bonus point.
They should not get carried away. It doesn't get much easier than this. Leeds cannot buy a win at any price and yesterday they capitulated again, as downhearted at the end as Cardiff had been at half-time. If it was a game of two halves it also illustrated a tale of two All Blacks.
At least Lomu is joining a club who know how to win, although not yet at any reassuring level of consistency. Now consider the experience of Justin Marshall, one of the great All Blacks scrum-halves. Whatever Leeds are paying him, and it's a lot, he deserves every penny.
During the Lions tour of New Zealand, Marshall was playing with the best team in the world and enjoying every minute of it. Since his move to Yorkshire he has forgotten how to spell success. His last act, in the dying minutes, was to flip out a pass between his legs, close to the Cardiff line. In thought and deed it was too much for a team-mate who dropped the ball.
Marshall trooped off to sympathetic applause from the crowd, having given his all and it was nowhere near enough. Phil Davies, the Leeds coach, has just turned 42 but he probably feels a lot older. Talk about kicking a man when he's down. "Big Phil has played a large part, literally and metaphorically, in the establishment of Leeds as a true fighting force," Robert Norster, the Cardiff chief executive, wrote in the programme.
His words were ringing true when Marshall aid-lifted Leeds into a useful lead. A typical break in midfield created a try for Andre Snyman at the posts midway through the half and when Leeds looked as if they were about to score another, Marshall, who was not in possession, found a massive anchor attached to his leg in the shape of Craig Quinnell. "A professional foul," said Craig's brother Scott, who was commentating for television.
Released from his chains, Marshall dropped a goal from no more than 10 yards and Craig escaped with a lecture. Gordon Ross added a penalty and Leeds were seven points in front. Nicky Robinson, who kicked two penalties in the first half, opened the second with a third before Cardiff cut loose with four tries in 22 minutes.
The first came from Robin Sowden Taylor who squeezed in at the left corner after taking a pass from Martyn Williams. At the time Leeds were down to 14 men. The hooker Rob Rawlinson had gone off with a cut head and by the time his replacement Gordon Bulloch appeared, Cardiff had scored. Shambolic.
Leeds were caught by another sucker punch when Gareth Williams took a quick throw to the front of a line-out, accepted a tap back from Quinnell and scampered 30 yards down the left touchline in the manner of a demented badger.
In a season that is going from bad to worse, Leeds replaced Ross with Roland de Marigny and the new stand-off's first act was to have a kick charged down by Craig Morgan. A couple of smart passes later and the prop John Yapp was touching down.
Cleverly varying their line-out near the Leeds line, the pack coiled up for the pushover: an irresistible force against a by now very movable object and when Blues crashed over en masse, the player at the bottom with the ball and the try was Gareth Williams.
That secured the bonus point and Robinson's excellent goalkicking brought him 20 points with four penalties and four conversions. Perpignan in France in round two is going to be a different kettle of poisson.
Cardiff: R Williams (capt); C Czekaj, J Robinson, M Stcherbina (T Davies, 80), C Morgan; N Robinson, M Phillips (R Powell, 74); J Yapp, G Williams, M Jones, C Quinnell, R Sidoli (D Jones, 73), R Sowden Taylor (K Shubert, 76), A Powell, M Williams.
Leeds: T Stimpson; A Snyman, R Vickerman, C Jones, T Biggs; G Ross (R de Marigny, 65), J Marshall (capt; D Care, 75); G Kerr, R Rawlinson (G Bulloch, 64), R Gerber (J Isaacson, 55), S Morgan, T Palmer, N Thomas (D Hyde, 61), J Crane, R Parks.
Referee: R Dickson (Scotland).