Germany captain Philipp Lahm on Wednesday said his side must drastically improve their defence or risk an early World Cup exit.

"We have to work especially on our defence," the Bayern Munich star told German daily Bild with Germany facing Portugal in their opening Group G game on June 16 in Salvador.

"Recently, we have conceded far too many goals and allowed our opponents too many chances.

"We must pay more attention to our defensive formation and the whole team is needed for that."

Traditionally, Germany have relied on rock-solid defence at major tournaments, but they have leaked goals in recent games, namely the 3-3 friendly with Paraguay last August and the 4-4 World Cup qualifier against Sweden in October 2012.

The 30-year-old Lahm admits this could well be his last chance to win the World Cup title having reached the semi-finals at both Germany 2006 and South Africa 2010.

"I do not want to go out in the semi-finals again or visit Brazil to soak up the sun," he said with Germany having finished third at the last two World Cups.

"I have a clear goal, to achieve the biggest possible success and win the World Cup.

"We have the necessary punch to win the title, but we must be sure that the talent and ego of every individual provides only for the team's benefit."

Germany started their 10-day pre-World Cup training camp in the north Italian Alps on Wednesday and face two final warm-up matches against Cameroon on June 1 in Moenchengladbach and Armenia on June 6 in Mainz.

A German Football Association (DFB) spokesman said Lahm is expected to join the squad in the resort of St. Leonhard on Friday having picked up an ankle injury.

Arsenal defender Per Mertesacker will arrive in the next few days after becoming a father for the second time.

Vice-captain Bastian Schweinsteiger arrived with the squad as he recovers from an inflamed knee ligament and his Bayern Munich team-mate goalkeeper Manuel Neuer, who has a shoulder injury, will travel to the south Tirol only after receiving treatment.

Lahm meanwhile says he hopes to continue working with Germany's head coach Joachim Loew after the World Cup with the 54-year-old under contract until after Euro 2016.

"The fact is that he has a contract, as a team we work well together with him and he always prepares us very well tactically," said Lahm.