A proud Basque, Unai Emery takes part every year in his home town's commemorations of a famous victory over the French, but on Wednesday he will be very much in the French camp.
The Spanish coach's Paris Saint-Germain take on Barcelona in the Champions League with an unbelievable 4-0 lead after Emery's battle tactics pulled off one of the biggest shocks of the competition in the last 16, first leg.
Emery will be looking to seal progress to the quarter-finals when leading his team into the lion's den of the Camp Nou.
And this time, Emery's home town of Fuenterrabia will be supporting the French.
The 45-year-old Emery prays at the Shrine of Our Lady of Guadalupe overlooking the fishing port on the Basque coast, according to his friends.
Every year he attends festivities there in early September to mark the victory in 1638 over French forces who laid siege to Fuenterrabia.
Football is a family business for Emery, who started playing on the town football pitches, near the picturesque port and houses with coloured terraces where the Ikurrinas Basque flag often hangs.
His grandfather won the Spanish Cup twice with Irun and his father played for Deportivo La Coruna. Both were goalkeepers.
- Coach's prayers -
But Emery was never a top player, unlike many of his coaching counterparts, having got stuck in the Real Sociedad reserve team during five seasons at the club.
He did play five first division games in 1995-1996 but then moved to second division teams Toledo, Ferrol and Leganes.
"He was small, very light, but skillful, he was good on the ball, a good dribbler and he had a good vision," said Mikel Jauregui, coach of the Hondarribia team, who later became Emery's assistant when he was coach at Valencia and Spartak Moscow. The two remain close friends.
Emery went to Lorca in third division, where at the age of 32 he started a meteoric rise as a coach that culminated in him winning three straight Europa League titles with Sevilla from 2014-2016, catching the eye of the PSG power-brokers.
While a modest player, Emery has proved a brilliant coach. PSG believe that this year is their best chance yet of getting at least to the Champions League semi-finals for the first time.
"Unai had character, he was debating all the time. If the game plan did not suit him, he would argue with the coach," said Mikel Etxarri, who was Real Sociedad coach when Emery was there.
"He was kind of the team leader, the game strategist who gave orders on positions."
Jauregui also described Emery as a "very competitive" coach. "He is a worker, passionate, who thinks about football 24 hours a day."
Fuenterrabia is now very proud of its most famous footballing son even though he has gone to France to find international fame.
"People like him a lot and he comes here often," said Jauregui. "People are proud of everything he has done. He was not a top player but he went out and got to the top."
Apart from praying at the shrine, Emery is seen with his family and friends in the town, walking on the sea front. All turn out for the annual celebration of the win over the French invaders.
"It is something he keeps to every year," said a cousin, Inaki Artola. "I reckon that when he is praying on the touchline he must be saying 'please let the date fall on a day when I don't have training so that I can go to the festival."
Jauregui is backing Emery to become a legend among European managers.
"I don't know with which team, but I am convinced that he is going to win the Champions League."
PSG will be hoping he achieves that this season, but not before completing a famous victory over Barca.