MOSCOW

Defending World Cup champions have been finding it hard to get out of the group stage lately, and Germany is proving no exception.

The 2014 champions, ranked No. 1 in the world, were exposed defensively and surprisingly beaten by Mexico 1-0 on Sunday, putting its hopes of advancement in doubt.

Well, not everyone is in doubt.

“We will make it,” Germany coach Joachim Loew said. “There’s no reason to fall apart because you lose one game.”

Hirving Lozano scored the lone goal in the 35th minute, picking up Javier Hernandez’s pass inside the penalty area and beating Mesut Ozil before shooting past Germany goalkeeper Manuel Neuer from 10 yards.

The goal decided the match — a match Germany didn’t expect to lose.

“I don’t know if it’s the biggest victory in (Mexico’s) history, but one of the biggest for sure,” Lozano said. “My teammates and I did some great work. We all ran our hearts out. This is the result of all that hard work.”

Three of the previous four defending World Cup champions failed to reach the knockout stages, France, Italy and Spain. Two of them lost their opening matches while the Italians had to settle for a draw.

The Germans are bidding to become the first team to retain the World Cup title since Brazil in 1962, but have now won only one of their last seven games in all competitions. They hadn’t lost an opening game since the then-West Germany fell 2-1 to Algeria in 1982.

Mexico had never beaten Germany in a competitive match but was transformed from the team which lost to the Germans 4-1 in last year’s Confederations Cup, conceding twice in the opening eight minutes.

Lozano, a 22-year-old forward nicknamed “Chucky,” got Mexico going with a deflected shot over the bar in the first minute. That set the tone for Mexico to torment Germany on the counterattack, with Lozano taking full advantage of right back Joshua Kimmich’s tendency to go forward.

After Lozano’s goal, Mexico goalkeeper Guillermo Ochoa pulled off a spectacular save to keep the score even, palming Toni Kroos’ shot onto the crossbar.

Serbia 1, Costa Rica 0

With a curling free kick that decided the outcome of the match, Aleksandar Kolarov immediately drew some comparisons to Cristiano Ronaldo.

The Serbia captain’s leftfooted strike proved to be the difference in a victory over Costa Rica. It came two days after Ronaldo scored a similar goal to give Portugal a 3-3 draw with Spain.

After Costa Rica midfielder David Guzman was handed a yellow card, Kolarov stepped up and curled his shot over the wall and into the net in the 56th minute. Keylor Navas, the Costa Rica goalkeeper who plays for Real Madrid, stretched but couldn’t stop the swerving ball.

Brazil 1, Switzerland 1

Brazil joined the list of big teams struggling to win their opening matches.

The five-time champions were held to a draw by Switzerland.

Philippe Coutinho, who was making his World Cup debut, gave Brazil the lead in the 20th minute with a volley that bounced in off the right post. Steven Zuber then headed in the equalizer in the 50th. Mexican referee Cesar Ramos dismissed complaints that Zuber had shoved defender Miranda before getting to the corner from Xherdan Shaqiri.

Ramos also ignored a penalty claim late in the second half when Gabriel Jesus was wrestled to the ground by Switzerland defender Manuel Akanji.

Swiss players ended up with three yellow cards, and 10 of the 14 fouls they committed were on Brazil forward Neymar.

Switzerland dominated the midfield for long spells against a Brazil team that had been keen to start with a win after its disastrous exit as host in 2014.