It is the ultimate test for any parent.
Two sons playing on opposite teams in a match. Who are you rooting for?
But this is not a kickabout in the local park or a schools’ match. This is a game at the World Cup.
There are four sets of siblings playing for different nations on the biggest stage of all, including Desire and Guela Doue who could face one another this summer.
Born to a French mother and an Ivorian father in the French city of Angers, the brothers play for Paris St-Germain and Strasbourg respectively.
They have taken different paths in international football, with two-time Champions League winner Desire, 21, turning out for France and overlapping full-back Guela, 23, playing for Ivory Coast.
“We tell each other everything and have no secrets,” Desire told French football programme Telefoot about his relationship with his older brother.
“He’s such a massive support for me in my daily life.”
But could their close bond be tested in the United States?
Should France finish runners-up in Group I and Ivory Coast finish runners-up in Group E, the pair will face one another in the last-32 stage in Arlington, Texas, on 30 June.
When Ivory Coast defeated France 2-1 in a pre-World Cup friendly on 4 June, Guela sang both countries’ national anthems before the match.
Desire, who had won won the Champions League with PSG five days earlier, was an unused substitute.
“It’s a shame I didn’t get to play against [my brother], as this was our first France-Ivory Coast match, but I’m happy, and he isn’t too fed up,” said Guela afterwards.
There has been only one previous case of siblings squaring off against each other at the World Cup,, external and it happened in back-to-back tournaments.
Jerome Boateng of Germany faced older half-brother Kevin Prince of Ghana in Johannesburg in 2010. Germany won 1-0. Four years later, the pair were on opposite sides again in Brazil when the group game ended 2-2.
Desire and Guela could well be next.
So, who are the other brothers appearing at this World Cup?