A friendship forged by domestic success last season matters little in a continental collision.
During 2011/12 at Al Ain, Omar Abdulrahman and Yasser Al Qahtani were brothers in arms, providing the ammunition that blazed the club to a 10th Pro League title, and their first in eight years.
Yet they cross paths at the Tahnoun bin Mohammed Stadium as former teammates with immediately separate goals; the comrades have become combatants.
"Outside the 90 minutes he is a brother, a friend," said Abdulrahman ahead of Al Ain's Asian Champions League opener against Al Hilal, Al Qahtani's current club.
"But inside the pitch we don't know Yasser." Even Al Ain's most dedicated discipline would struggle to erase memories of Al Qahtani's contribution last year. The Saudi Arabian striker, then on loan from Hilal, managed a modest seven goals in 15 league matches, but it was his double against Al Jazira in April that clinched the championship.
Understandably, Al Ain requested he remain in the Garden City, but Al Qahtani chose to return to his parent club in Saudi Arabia. He has continued to plunder, scoring 12 times in 20 appearances.
Abdulrahman recognises the impending threat.
"I wished he stayed in Al Ain, all of us did," the playmaker said. "Because last year we really made use of his experience, although now we simply wish him all the success and welcome him back to play against us.
"But we're not playing against only Yasser, but the whole Hilal team. And if we get the three points it's a good start, the next step."
The Al Ain board, though, is thinking in giant leaps, specifically the recovery of the Champions League title secured a decade before this latest assault.
Al Ain were crowned kings of the continent in 2003, when Mohammed Omar's first-leg strike against Thailand's BEC Tero Sansana proved the decisive goal as they triumphed 2-1 on aggregate.
They would reach the final again in 2005 only to be beaten, but in three appearances since 2007 Al Ain have failed to negotiate the group stages. This year, with Abdulrahman the creator in chief alongside the prolific goalscorer Asamoah Gyan, the club expects.
"[The class of 2003] won the Champions League and many more titles, but we too have won, with the Pro League and the President's Cup," Abdulrahman said. "We're not drawing comparisons with them, only trying to make use of their experience, benefit from their instructions, to reach the highest point of success. But now we're not concentrating on the trophy, just the Hilal match."
On Friday, Hilal secured the Crown Prince Cup, only 24 hours after Al Ain had experienced their first defeat in 15 league matches.
However, that 1-0 home reverse to Dibba Al Fujairah, the division's bottom club, has been promptly consigned to the past. "We lost to Dibba but the following day we forgot everything about it," Abdulrahman said.
"It became the past and we can't change it. It's true Hilal achieved something good, but at Al Ain, the players love a challenge."
That challenge, beginning against a familiar foe, is to reacquaint themselves with former glories.
Follow us @SprtNationalUAE