BERLIN (AP) -- Christoph Metzelder is just 25 and already he's Germany's senior defender.
Metzelder returned in October from an Achilles' tendon injury that sidelined him for nearly three years. Since, he has struggled with more minor injuries, form and timing.
This is the guy who is going to have to stop Luca Toni when the host nation takes on Italy in Tuesday's semifinal at the World Cup?
"It won't be easy," Metzelder acknowledged. "We won't get too many chances, and we can't allow any. At this stage the focus is more on not conceding."
Toni led the Italian Serie A with 31 goals at Fiorentina last season, and has two in Germany, both coming during Italy's 3-0 quarterfinal victory over Ukraine when the Azzurri's offense finally got on track.
And Toni is not the only threat. The Italians have depth at forward, able to choose from Francesco Totti, Alessandro Del Piero, Filippo Inzaghi, Alberto Gilardino and Vicenzo Iaquinta. In their last meeting, a friendly in Florence in March, Italy won 4-1.
And so far this World Cup, the Italians have allowed only one goal, an own-goal against the United States, meaning not allowing the Azzurri to score first is imperative.
That responsibility will fall to the 6-foot-3 Metzelder, who is paired with the even taller (6-5) Per Mertesacker in the middle of the German defense, with Philipp Lahm to the left and Arne Friedrich on the right.
"The back four's prime objective will be to prevent them from scoring," said Metzelder, who has stopped shaving for as long as Germany stays in the tournament. "I think our forwards will be in for the same kind of treatment. So it will be a kind of waiting game."
Metzelder is not a novice to the World Cup, grabbing a starting role in 2002 after regulars Jens Nowotny and Christian Woerns were injured shortly before the tournament began. He helped Germany all the way to the final, where it lost to Brazil.
But the Achilles' tendon injury required two operations and he missed 32 months. When he returned to Borussia Dortmund, he struggled to regain form, spent a lot of time on the bench and was not included on last year's Confederations Cup squad.
Germany coach Juergen Klinsmann had faith, though, and invited him back in October. A torn right calf muscle in May continued to raise questions.
If Germany's young and inexperienced defense was considered the team's vulnerability at the start of the World Cup, it has grown up in the past three weeks.
After yielding two goals in its World Cup opener against Costa Rica, the side has allowed only one in the four games since, and that came from a set piece during its quarterfinal victory over Argentina.
Until the quarterfinal, Germany had played a fast, attacking style, but preferred a more patient, cautious approach against Argentina, hardly allowing -- or taking -- any chances.
The team is expected to take the same approach against Italy.
"I think the Italy match will be fairly similar," said assistant coach Joachim Loew, a tactician who creates the team's game plan. "They are wanting to score on the counter. It's their style of play.
"A little more caution will be the motto, but with the Dortmund fans behind us, we'll definitely take every chance to make life difficult for Italy."