Germany coach Joachim Loew said there was no greater challenge than defending the World Cup title ahead of the reigning champions' opening game against Mexico on Sunday.
No country since Brazil in 1962 has successfully retained the World Cup, with Italy the only other side to win back-to-back trophies, in 1934 and 1938.
"It's the most difficult feat and history has demonstrated that, no one in 60 years has done it," Loew told reporters at the Luzhniki Stadium on Saturday.
"Teams develop and change, players finish their careers and you must bring in new players which makes it the most difficult achievement."
Nine of the players selected by Loew for Russia were part of Germany's title-winning squad four years ago, although the likes of former captain Philipp Lahm, Bastian Schweinsteiger and Miroslav Klose are all gone.
"As far as hunger and ambition, it is there," said Loew, whose side will also meet Sweden and South Korea in Group F.
"It's palpable and you can sense it is there among the players.
"The tension is rising, you can see it is a very special occasion for all of them. There's no greater occasion for a player than to play in a World Cup final, but we must focus on each individual match and not think too far ahead of ourselves.
"We want to get the message out that we want to win this opening match and then go from there." Germany are notoriously strong starters at the World Cup, winning their last seven opening matches at the tournament while losing just once -- 2-1 to Algeria in 1982 -- in 18 total appearances.
"I can only speak about the times when I was coach, but we have often won the first match in my time," Loew said.
"In the run-up to the tournament we've had to accept some friendly losses and training has been tiring and wearing on the players.
"But in the first match we normally bring to bear our abilities on the pitch, it's linked to the confidence of our players.
"Everyone believes in themselves and the path we've come along together. It's always been good for us if we've started the tournament with a victory."
Ozil, Neuer ready
Germany took maximum points in qualifying for Russia while scoring a joint-record 43 goals, but the four-time world champions won just one of their six warm-up games.
However, they thumped Mexico 4-1 in last year's Confederations Cup semi-finals and have only been beaten once by Sunday's opponents in 11 previous meetings.
"The first match (at the World Cup) is always difficult with the break after the qualifiers, there are certain things you think about and not everything works out during friendlies," said Loew, who downplayed the notion of facing any extra pressure as holders.
"At the end of the day it's not really important," he said. "Everyone wants to play well at the start and perform to their best, this is the same irrespective of previous titles."
Loew sounded confident Mesut Ozil would be fit to feature after sitting out Germany's 2-1 win over Saudi Arabia eight days ago with a knee injury.
"He has had two extra training sessions this week, my overall impression is good and that he is fit."
The Germany coach also said goalkeeper Manuel Neuer looked his old self after winning a lengthy injury battle following eight months out with a broken foot.
"Over the last three, three-and-a-half weeks, I have seen a very focused Manuel Neuer. He's been very concentrated and involved in all training sessions during training camp," Loew said.
"He looks very confident during training and like the Manuel Neuer we've always known.
(PTI)
