Athletic Club manager Ernesto Valverde has said two players have given Arsenal an advantage ahead of their Champions League clash on Tuesday.
The La Liga side welcome the Gunners for their first game on the continent this season.
Last season, Arsenal went all the way to the semi-finals, where they lost to eventual champions Paris Saint-Germain.
Speaking on Monday ahead of the game, Valverde described Mikel Arteta as “one of the best managers in the world”.
Both Martin Zubimendi and Mikel Merino played for Athletic’s arch-rivals Real Sociedad before moving to England.
Valverde said: “They’re the same players, so this experience will obviously help them improve further.
“I think they’ve both started off on the right foot at Arsenal, especially because they’re used to a high pace and have the resources to handle themselves.
“We’ve already seen that Zubimendi has just arrived and is already shining there. I don’t know if he’ll have any special motivation.
“They already know us, so they may have an advantage in that sense, but hey, we know them too.”