The Barcelona forward had scored four goals prior to his nation's 2-1 victory over Colombia in the quarter-final on Friday, but the 22-year-old was ruled out for the remainder of the tournament after picking up a back injury following a collision with Juan Camilo Zuniga.
Brazil captain Thiago Silva will also miss the game through suspension, but rather than revel in the prospect of facing a weakened Brazil side, Lahm has said that it will be a shame not to face the hosts at full strength.
"First of all, it is a pity that both are missing," he is quoted as telling Bild am Sonntag by Goal.com.
"I'm especially sorry for Neymar. To miss a semi-final at a home World Cup through injury is a bitter blow.
"In a World Cup you always intend to compete with the best. That's why I would have preferred to play against Brazil with Neymar, but I believe that Brazil has enough players who can step into the breach for him."
Brazil and Germany will face each other in the first World Cup semi-final in Belo Horizonte on Tuesday.