Gerard, the young Spanish midfielder, started it off, with an interception in the 61st minute. Stretching out his leg, he diverted a pass from Bordeaux's Francois Grenet into the path of Lopez, who was moving into the inside- left position. Lopez controlled it with the outside of his left foot, beating Nisa Saveljic in the same movement. Then he stopped and looked up, noting Kily Gonzalez moving to his left and Adrian Ilie to his right.
When Kodjo Afanou closed in to make a challenge, Lopez used his left foot again, to bring the ball across his own body, swivelling away from the tackle with elegance and economy of movement. A sudden spurt brought him to within five yards of the penalty area. As he accelerated and straightened his run, he stroked the ball to Francisco Farinos, 10 yards away to his right, inviting the return pass. Instead, profiting from the momentary hesitation in the defence caused by his team-mate's explosive movement, Farinos struck a left-footed shot from 25 yards across Ulrich Rame and inside the angle of the bar and the far post.
And Lopez wasn't finished. In the 69th minute he started on a similar run from left to right, taking Grenet and Afanou with him, leaving only Saveljic to counter the far-post runs of Ilie and Gaizca Mendieta. This time Lopez carried the run further. When he used his right foot to chip the ball back across the goalmouth and over the sole defender, Ilie was there to ram it home.
The single instant touch with which he sent Gonzalez in for Valencia's third and final goal in the last minute of the match was stunning in its simplicity and efficiency. Gonzalez, wide on the left, flicked the ball to Lopez who, barely moving, used the outside of his left foot to flick it back into his path. Gonzalez swung his foot and the ball was rippling the roof of the net with Rame helpless once more.
Not surprisingly, Claudio Lopez is among the 55 players from whom France Football will choose the European player of the year. His achievements in the past 12 months have made him a target for more glamorous clubs. Yet of all the superstars thronging the continent's major teams, the 25- year-old Argentinian is probably the least known to English fans, despite taking part in the tumultuous World Cup match in St-Etienne 18 months ago.
Although he was by then firmly established as the preferred partner for Gabriel Batistuta, Lopez didn't achieve a great deal in that game. By the time the penalties came round, he had been substituted. He was on the losing side in the quarter-final, but not before he had scored the equaliser which kept Argentina in the match until Dennis Bergkamp's 89th- minute miracle gave the Netherlands the victory.
"He may not be so well known in England," his Valencia team-mate Joachim Bjorklund said admiringly last week, "but they certainly know him here in Spain, especially after last year, when he scored so many goals."
It was his third season with Valencia, where he had arrived from Buenos Aires after distinguishing himself in the colours of Estudiantes and Racing Club. In his first year in Spain, he scored five goals in 40 matches. In his second, the haul rose to 12 in 36. And in his third, an impressive 30 in 40 - six of them in three games against Barcelona.
Two weeks ago he scored once more in Valencia's latest defeat of the champions, giving Barcelona's players more reason than ever to appreciate the significance of the nickname which has stuck with him since childhood.
He is known, sometimes even on the team sheet, as El Piojo - the Louse. That doesn't sound very nice. But it means that he is small and quick, elusive and irritating, and carries a nasty bite which can have unpleasant consequences.
"He's a good player," Bjorklund said. "One of the fastest I've seen on a football pitch. When he gets into the spaces, as he seems to do in the European matches, he's lethal."
Tonight at Old Trafford, Manchester United may count themselves lucky to be spared the challenge posed by his partnership with Ilie, which blossomed with the arrival of the Romanian - known as El Cobra - at the club in January 1998. Both men are blessed with lightning speed, and Ilie adds the power to the deftness of Lopez.
But even without his partner, Lopez can make the difference. Last Saturday night, in a drab game at home against Seville, deservedly the league's bottom club, he was constantly active. Mendieta wore the captain's armband, but Lopez was the team's focal point. After six minutes he took a corner on the right, whipping the ball in with his left foot. As it whizzed over the defence and dipped inside the far post, Juan Sanchez hardly needed to get a touch to open the scoring. Valencia completed their scoring after 70 minutes with the sort of lightning counter attack which is their trademark. Sanchez broke down the right and pushed the ball inside the full back to Jocelyn Angloma, whose low cross was teed up by Gerard for Lopez to shoot home from 15 yards, taking careful aim with his right foot.
He runs with his head forward and his eyes held steady, like a gun-dog on the scent of something. Sometimes he revives the ancient art of coming to a halt in front of a defender with the ball at his feet, feinting once or twice and then, having hypnotised his opponent, beating him from a standing start, like Stanley Matthews used to do. If you take your eye off him for an instant, he'll be gone; the next time you seen him, perhaps only a couple of seconds later, he'll have turned up on another part of the pitch altogether.
Despite offers from more glamorous clubs in Italy and Spain, Lopez has chosen to stay at Valencia, following the example of Mario Kempes, another great Argentinian forward. "I think the football we play suits him quite well," Bjorklund said. "I don't know what he gets paid, but I'm sure he's got a good deal here." The Swede squinted up at the sun, shining out of a flawless blue sky on the club's training ground, only a 10-minute drive from the Mediterranean. "And it's a very good place to live."
Those who see him only on television will never get a true idea of Claudio Lopez's talent, or of the problems he poses defenders. On the ball his touch makes him a pleasure to watch, but without it his contribution is equally telling, and marked by great unselfishness. As soon as his team- mates win possession he is starting to make a run, often across the face of the opposing defence, dragging the centre backs all over the place. The television camera, following the ball, sees only the end product.
But his sense of the game's fluid geometry is so good that you can watch him just to admire the angle of his runs.
Batistuta, Ronaldo and Christian Vieri may have bigger reputations and fatter contracts. But if you wanted to get Michael Owen, say, to sit down and learn something from another forward, Claudio Lopez might be the one you'd chose.