MOSCOW -- Germany must shrug off a rocky World Cup build-up as they begin the defence of their title on Sunday against a vastly experienced Mexico side jolted by their own pre-tournament scandal.

While Manuel Neuer finally won his lengthy fitness battle after more than eight months out, Mesut Ozil and Ilkay Gundogan were jeered by Germany fans in recent friendlies after posing for a photograph alongside Turkish President Recep Tayyip Erdogan.

Real Madrid midfielder Toni Kroos said what is discussed on talk shows should not concern the players, adding: "We are here to play football."

The form of Joachim Loew's side is another concern though, an unconvincing win over a Saudi Arabia outfit thrashed 5-0 in the World Cup opener represents Germany's lone victory since romping through qualifying with maximum points.

"We need the greed, the fire -- it's part of what makes things go off with a bang sometimes in training and on the playing pitch. We will have to fight for every inch," said defender Jerome Boateng.

"I think we're known as a team that starts well," he added, saying he feels "better from day to day" after returning from a groin injury.

Germany defeated Mexico 4-1 on the way to lifting last year's Confederations Cup trophy but Kroos believes that result is of little significance now. 

"We shouldn't underestimate them, even if it was a clear win at the Confederations Cup last year. We're taking this very, very seriously and, once more for emphasis, because it's our first game at the World Cup."

Germany are trying to become the first team in 56 years to successfully defend their title, after Brazil in 1962, but Mexico defender Carlos Salcedo believes their Group F opponents are not invincible.

"We speak a lot about them and we consider them clearly superior," said Salcedo, who signed a four-year deal with Eintracht Frankfurt in May after spending the past season on loan with the Bundesliga club.

"But no one is unbeatable. In football, the difference between levels has decreased and there are lots of other factors.

"There are just two or three players who can score two or three goals per game, (Lionel) Messi, (Cristiano) Ronaldo and Neymar, who can shake things up with a stroke of individual genius."

Like Germany, Mexico qualified with ease for a seventh consecutive World Cup after punching their ticket to the finals with three matches to spare.

Rafael Marquez, who will retire after the tournament, is set to become just the third player -- after compatriot Antonio Carbajal and Germany's Lothar Matthaus -- to feature at five World Cups.

But a number of Mexico players found themselves embroiled in controversy following a farewell party with about 30 prostitutes ahead of their departure for Europe.

Nine members of the World Cup squad reportedly partied with the women at a private compound in Mexico City following the team's 1-0 win over Scotland earlier this month.

Mexican officials ruled out sanctions against the players involved because they attended the party in their free time, but the incident echoed similar scandals in recent years.(AFP)