Rafael Marquez is by far the most experienced player on Miguel Herrera's side, however he will have a great deal of pressure during the World Cup.
Marquez became an icon in 2003 when he arrived in Barcelona after four successful seasons with Ligue 1 heavyweights Monaco.
The centre-back quickly became an undisputed starter and sometimes even played as a defensive midfielder, broadening his already bright reputation.
In his seven years in Spain he won it all. Four La Liga titles, three Supercopas de Espana, two UEFA Champions League and one Copa del Rey, UEFA Super Cup and a FIFA Club World Cup.
He became the stalwart of Mexico's defense, too. His leadership and fine touch put him in the spotlight quickly.
At age 35 Marquez is back in the national team. As of now, he is the only one who has already secured his spot in the World Cup squad. After a training session, Herrera told Mexican media last January:
I haven't secured a place to anybody, for me the only one who has a spot right now is Rafa Marquez, hoping he arrives in good shape (to Brazil) he will be the captain.
Fantastic, but Marquez is no longer a kid and his physical condition will be tested—especially against Cameroon and Brazil.
The African side is strong and fast. The Indomitable Lions' age average is 26.2 years old and they have some promising footballers like Lorient's Vincent Aboubakar and Schalke's Joel Matip, plus established footballers such as Samuel Eto'o and Alex Song.
Cameroon may be weak in the back line, but the attacking zone is solid.
On the other hand, the host brings one of the strongest sides we have seen. Neymar is set to have his greatest performance with the national team after his display of talent and skill at the 2013 Confederations Cup. Add a midfield commanded by Oscar, Paulinho and Luiz Gustavo and the explosiveness and creativity come in bulk.
For what we have seen in the past five games, Mexico's defense is not prepared to come across these type of players.
Marquez proved that what he has in experience he lacks in fitness. He has been a standard bearer of Club Leon, hence appearing in two simultaneous tournaments: 2014 Clausura and the Copa Libertadores.
Physically, he is struggling. In El Tri's latest friendly against Nigeria, Emmanuel Emenike surpassed him constantly, his stride and strength were enough to expose the Mexican defender.
It is not only an issue of musculature. Herrera's 5-3-2 system gives the full-backs the chance to run through the flanks and join the attack, which leaves the centre-backs guarding the box by themselves.
In this task, Marquez partners with Hector Moreno, who has always been sharp, and Diego Reyes, who is not receiving much playing time with Porto. Francisco Rodriguez is an alternate partner, who is far from being the imposing footballer he used to be in 2010.
Herrera needs to find another consistent centre-back or the backbone will suffer a lot. Hence Marquez, hence Mexico.
If addressed correctly, this issue can be shut before the World Cup, but since Herrera has been calling basically the same defenders it seems like a long shot.