The player idolised by Lionel Messi as a youngster has been integral to the Portuguese club's run to the quarter-finals of the Champions League.
Pablo Aimar's 'genius' has proven inspirational to Benfica
Perhaps it is his benevolent face. Perhaps it is his small, wiry, apparently delicate frame.
Perhaps it is just that Pablo Aimar's style of football is so obviously geared towards the creative and the subtle that Joao Gabriel, Benfica's director of communications, was persuaded at the weekend to back up his outrage at the club's 32-year-old Argentine being sent off against Olhanense with the claim: "Aimar has never received a red card before in his whole career."
Gabriel's point was that a controversial refereeing decision had been made even more contentious because of the player's fine disciplinary record. The trouble was, Gabriel's statistics were incorrect. Gentle, dainty Aimar had, in fact, been sent off before in his career, although, granted, the last time was nine years ago.
Benfica's 0-0 draw at modest Olhanense on Friday night, complete with the disputed red card for their most garlanded player, has irritated the Portuguese club ahead of tonight's Champions League quarter-final first leg against Chelsea.
But that may be no bad thing. Indignation has become part of Benfica's psyche over the last three years of domestic jousting with Porto for national supremacy, an emotion nourished by the coach Jorge Jesus.
They are still the country's biggest club, which is partly why distinguished footballers who have thrived across the border in Spain regularly join them.
The squad who will take on Chelsea in Benfica's first last-eight appearance in the European Cup for six years include Javier Saviola, once of Barcelona and Real Madrid; Joan Capdevila, a Champions League semi-finalist with Deportivo La Coruna, good enough to have been Spain's left-back when they won the last World Cup and Euro 2008 but mostly second choice in his position at Benfica; and Javi Garcia, who anchors midfield, as he did occasionally as a young prospect at Real.
But the most effective swoop made by the so-called Eagles of Lisbon across their eastern border in recent years has been the capture of Aimar, from Real Zaragoza, in 2008.
"He is a genius for anybody who appreciates that football is an art," Jesus said of Aimar. He was describing the player's ability to see the pass that is invisible to others, to spot pockets of space hidden to most.
Benfica's coach is by no means the most important provider of testimonials for Aimar.
"He was my idol when I was growing up," Lionel Messi said. Sir Alex Ferguson, the Manchester United manager, extended a eulogy towards Aimar when the English champions met - and were effectively eliminated by - Benfica in the group phase of this season's Champions League.
"I was really proud when Ferguson said good things about me," Aimar said.
Aimar fits, much like Messi in certain aspects of his football, into the Argentine tradition of the diminutive, crafty, imaginative inside forward, operating just behind a central striker. The fabled examples would be Diego Maradona and Messi.
Aimar has won over 50 caps for his country, and was a key part of the Valencia team who won two Spanish League titles and the 2004 Uefa Cup under Rafa Benitez's management.
Although Benitez came to cherish Aimar's ability as a match-winning provider of assists, he had phases where he seemed cool on the player.
Claudio Ranieri, the Italian coach who replaced Benitez at Valencia, was dismissive of him for being insufficiently physically imposing.
Doubts about his hardiness resurfaced at Zaragoza, where Aimar spent much of his time injured. So there was an element of risk when Benfica opted for him as the successor to the retiring club legend, Rui Costa, four years ago.
He has had fitness setbacks, but the club in February happily extended his contract for another season.
"He is a great example to other players, always trains hard, be it for one, two or four hours and he usually manages to take what he has worked on into matches," says Jesus.
His instructions tonight will be to probe and use his experience. Jesus will not need to tell him to keep his cool. Aimar seldom gets into trouble with referees. Friday's red card was not unique, but it was a genuine rarity.
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