The connections between the two national team setups have become increasingly apparent in the two barren days between the last quarterfinal and the start of the last four.
A picture of Hazard and two of his three brothers, Thorgan and Kylian, has surfaced showing the Belgian trio wearing France shirts as children, and Hazard admitted that he grew up favouring France over Belgium because of the former's 1998 World Cup success.
"With my brothers, we have always been more supporters of France than Belgium because we grew up with '98", Hazard said.
Henry was part of the 1998 team that won the World Cup on home turf, scoring three goals in his first major tournament and converting a penalty in a nerve-rattling shoo-out against Italy in the quarter finals. A former English Premier League manager, Martinez wanted Henry to not only teach Belgium's players the finer points of the game but, perhaps more importantly, he wanted him to talk about winning with a team that had been weighed down by expectations.
"I feel that the most important aspect we worked on was the notion of being a team". But this is a hard situation, it is not easy for him'.
"But he did know that, from the time he was joining the management team and becoming assistant to Martinez, that could happen". "I am happy for him for everything that he went on to do".
Belgium is tournament's top scorer so far with 14 goals. They come in to the match on the back of an impressive, if somewhat nervy, victory over Brazil in the last round and the Spanish boss believes their preparations are starting to pay off.
"We've strived to be as good as we could be at worldwide level and it's taken us two years to get there".
"Like everybody, I was surprised when he got the job, but it was a masterclass the last night against Brazil", said Whelan.
Belgium has height and heading ability in defenders Vincent Kompany and Jan Vertonghen and Marouane Fellaini.
"He's a different player now, and he will be a star for the next 15 years". "Apart from goalkeeper I could tell you that he could not just play, he could perform at the highest level in any position. That's the quality that he has".
They will also have the likes of Kylian Mbappé and Antoine Griezmann.
"Belgium didn't arrive here by chance".
Belgium have been superb at this year's tournament, finally dispelling the idea that they are a group of talented players who are unable to work effectively as a team.
"Will they do something similar for us?" I don't think they will see the space to put those balls pass France's backline.
However, their backline will face its biggest test yet against a Belgian team that are top scorers at Russian Federation 2018 with 14 goals in their five games, with the strikes coming from nine different players - a record in diversity shared with the French team of 1982 and Italian side of 2006.
Arguably, France have had the slightly harder route, defeating Argentina 4-3 and then fellow South American side Uruguay 2-0 in the round of 16 and quarter-finals respectively.
What will he think when La Marseillaise is played on Tuesday in the St Petersburg stadium before a World Cup semifinal? With the sides hard to separate on paper, how they handle the pressure, and perhaps those little nuggets of inside knowledge, could make all the difference.