Aguirre celebrates after scoring Mexico's fourth goal
France's bid for men's Olympic football glory got off to a nightmare start with a 4-1 defeat by Mexico on Thursday, while a strong Spain side stuttered to a goalless stalemate with Egypt.
Sylvain Ripoll's France are looking for a first Olympic medal since winning gold in 1984, but collapsed in the second half at Tokyo Stadium.
"We're obviously disappointed with the result but also with the balance of our play," said former Lorient boss Ripoll.
"To compete, we would've needed a big performance, but that wasn't the case."
Mexico took the lead less than two minutes after the break through Alexis Vega, before Sebastian Cordova doubled their advantage in the 55th minute.
The 35-year-old captain Andre-Pierre Gignac, whose last game for the French senior team was the Euro 2016 final loss to Portugal, pulled one back from the penalty spot with 21 minutes remaining.
But any thoughts of a comeback were quashed as Uriel Antuna and Eduardo Aguirre netted late on for 2012 champions Mexico.
France now face a tough task to get out of Group A with a top-two finish, ahead of games against Covid-hit South Africa on Sunday and hosts Japan on July 28.
"The first thing we now have to do is digest this disappointment," added Ripoll. "We only have two days. There's no time to waste."
Spain also struggled, as a team featuring six players who reached the Euro 2020 semi-finals dominated possession but created few chances against Egypt in Sapporo.
The closest they came to a goal was when Real Madrid midfielder Dani Ceballos, who recently spent two seasons on loan at Arsenal, crashed a first-half shot against the post.
Spain, winners on home soil in 1992, next take on Australia in three days' time before their final Group C match with Argentina.
New Zealand made a successful start in Group B as Burnley striker Chris Wood, one of the three over-age players in the squad, secured a 1-0 victory over South Korea in Kashima with his 72nd-minute winner.
Reigning champions Brazil get their campaign under way later on Thursday against Germany.