Action in Mexico City, where for the first time the venue offers the necessary facilities for all disciplines to be contested at the same stadium, opened with a ceremony dedicated to Pentathlon Day.

It honoured De Coubertin, who founded the International Olympic Committee (IOC) and the sport of modern pentathlon which was introduced for the 1912 Olympics.

The UIPM is working to have the mixed relay included in the Olympic programme for Paris 2024.

The event today was contested by 16 nations and Germany defended their title despite putting forward a different pairing dubbed the "B-team".

Liebig and Langrehr built a lead in the fencing and continued to head the competition to the finishing line.

France's Emma Riff and Alexandre Henrard led after the swimming event but were closely chased by the Russians, Anna Buriak and Oleg Naumov, and Hungary's Michelle Gulyas and Gergo Bruckmann.

Liebig and Langrehr were dominant on the piste and finished the fencing event with 25 victories to five defeats.

They also added two points in the bonus round.

Hungary, the eventual silver medallists, were second with 21 victories and nine defeats.

Mexico and the Czech Republic manged perfect scores in the equestrian arena but Germany and France also posted solid scores of 293 points.

At the start of the laser-run, Germany had a 31 second lead over Hungary, who had another 35 second advantage over the next group.

The battle for bronze was the climax of the event as France posted the fastest laser-run time of 11min 41.70sec to secure the bronze ahead of the Kazakhstan and China teams that chased them.

"We had such good fencing and that was the basis of everything," said gold medallist Liebig.

"The whole day was perfect and nobody would have expected this because we are the 'B team', the underdogs, but we got it and it’'s awesome."

Silver medallist Gulyas was ecstatic to pick up Hungary's first medal of the Championships.

"Our whole day was amazing and we were really stable in every discipline of the pentathlon," she said.

"We can't describe how happy we are; it's an amazing thing to be second in a World Championship."

As France took the bronze, Henrard added to his gold medal from the men's relay and praised his 17-year-old partner in mixed who earned her first senior medal.

"I really want to congratulate Emma and thank her," Henrard said.

"She is really young and she did a wonderful job today.

"I was doing the men's relay yesterday so it was more complicated for me but I really want to congratulate her, because it's thanks to her that we are third."

UIPM President Dr Klaus Schormann praised the event organisers in Mexico City who received an award as part of the Pentathlon Day celebrations.

"Today we celebrated, for the first time in history, the Pierre de Coubertin Pentathlon Day and we awarded Horacio de la Vega and Juan Manzo with the Pierre de Coubertin Medal," he said.

"This mixed relay, in the wonderful Pentathlon Stadium provided by our hosts here in Mexico, has given us a lot of arguments to present to the IOC with regard to the 2024 Olympic Games.

"The Programme Commission of the IOC can see what we are delivering with a really strong multi-sport and combined gender team competition.

"You cannot do more than what was presented today.

"The Pentathlon Stadium has been a wonderful success and I have been listening to some of the athletes talking about it, and I can give a guarantee that this is the stadium format we will use until the Tokyo 2020 Olympic Games and afterwards."