It was not, at the very beginning, a promising partnership at all.
Indeed, the first time Iker Casillas and Pepe lined up together in the same Real Madrid defence in front of home fans, they looked like pair of slapstick comedians. First, the goalkeeper spilled a catch, the central defender slipped onto his backside, and Madrid went 1-0 down.
Things got worse that August day, in the second leg of the Spanish Super Cup against Sevilla. Pepe gave away a penalty with a careless handball, and picked up the first of his many Bernabeu bookings. For Sevilla’s third goal, he and Casillas collided with one another like wayward dodgems.
Little wonder that Pepe, then a new Real Madrid signing, observed later that the club he had joined, even with its highly-regarded goalkeeper “was a graveyard for central defenders".
Pepe was sent off later that night, as Madrid shipped five goals and lost the Super Cup 6-3 on aggregate. Yet, despite all the evidence, a formidable duo was to take shape. Pepe and Casillas won the league that season, one of nine prizes they lifted together in eight seasons at Madrid.
Now, almost 12 years on, in a different club’s jersey, Casillas, the most highly decorated goalkeeper of the 21st century, and Pepe, pantomime villain to some, supreme man-marker to others, will play their 236th match as teammates.
Casillas turns 38 next month, Pepe turned 36 in February, soon after he had been offered the chance to extend his career at Porto, the club that in 2015 gave Casillas an unexpected fresh lease at elite level once his place in the hierarchy at Real, the club he grew up with, had been eroded.
The pair will appreciate the irony of finding themselves – facing Liverpool with a semi-final place at stake – further advanced in this season’s Uefa Champions League than are the current champions, the Real Madrid where Casillas and Pepe each won three European Cups.
But they are also 2-0 down from the first leg, which is bound to stimulate the realisation that in a competition both have commanded so often, there may not be too many of these ties left.
Pepe, never timid in his challenges, was suspended for the Anfield leg, and his return on Wednesday night will be welcomed by Porto manager Sergio Conceicao, whose analysis of the 5-0 blitz Liverpool inflicted on Porto at the last-16 stage of the competition last year partly informed his decision to sign the veteran Pepe from Besiktas in January.
Casillas did not play in that crushing 5-0 defeat. In the past 12 months, he has also provided much evidence that, even after 20 years in high-pressure league football, the instincts that made him a World Cup-winning captain, twice a European champion with Spain, and time and again the saviour of Madrid are still sharp.
Casillas’ 17 clean sheets – from 29 matches – have given Porto by far the best defensive record in the Portuguese championship this season, and left them neck and neck with Benfica in the title race.
On Wednesday night, the old warriors must plot an improbable turnaround. Casillas and Pepe have known a few and will see in the chances, particularly for striker Moussa Marega, Porto had at Anfield, some grounds for optimism. Experience will also guide their motivational words in the dressing room at the Dragao.
They will remind colleagues Porto came back from 2-1 down to eliminate Roma last month, thanks to a dogged three 3-1 win, after extra-time, at the Dragao. And Casillas and Pepe have a catalogue of comeback tales they could relate from Madrid days, not least of how their working relationship began so badly and then flourished, all the way to winning every club prize they could grasp.
The Spaniard will gee up his teammates with carefully chosen phrases, a clap of the hands. Pepe, who spent three seasons with Porto from 2004 to 2007, is more likely to roar.
“Pepe has come here with all the commitment and motivation I always saw in him,” Conceicao said.
At the very least, Porto intend for Liverpool’s fabled front three – Sadio Mane, Roberto Firmino and Mohamed Salah – to sweat for their opportunities, and to remember what may be their last battle with the pugnacious Pepe and with king Casillas.