Jerome Boateng claims his Bayern Munich team-mate Manuel Neuer is irreplaceable as Germany's goalkeeper.
Neuer, the captain and a key figure for both club and country, has not played competitively since September due to a foot injury.
The 32-year-old was included in Germany's provisional squad for their defence of the World Cup, but must now convince head coach Joachim Low of his readiness ahead of the finals in Russia.
Marc-Andre ter Stegen has enjoyed an impressive season with LaLiga champions Barcelona, while Paris Saint-Germain's Kevin Trapp and Bernd Leno of Bayer Leverkusen are the other shot-stoppers in Low's 27-man preliminary group.
While acknowledging the abilities of Germany's alternatives, Boateng is adamant Neuer remains the best man for the job.
"It makes a difference whether Manuel Neuer is in goal or someone else," he told Kicker.
"Manuel is the best goalkeeper in the world, the others are also very good, Marc-Andre ter Stegen has done well, but Manu has a different charisma than anyone else.
"This is not a devaluation of the others at all, but Manu is just Manu."
Boateng, 29, also rejected suggestions he could consider calling time on his international career after the tournament.
He said: "I will not stop, because I have never won the European Championship in the [senior] team, only with the U-21s."