(Reuters) - Mats Hummels, re-vitalized and bounding with energy just days after he was flattened by flu and fever, rose from his sick bed then above his opponents to send Germany into the semi-finals of the World Cup on Friday.

Hummels scored the only goal in Germany's 1-0 hard-fought win over France at the Maracana, climbing above the defense to get his head on a free-kick from Toni Kroos and send the ball crashing into the net off the underside of the crossbar.

Hummels, a 1.92 meter (6ft 4in) central defender, also scored off a header in his team's opening World Cup match against Portugal and has become an unexpected attacking weapon for a Germany team brimming with talent.

"There is no secret," he said. "I have been lucky to stand in the right position.

His goal was all the remarkable given that Hummels missed Germany's Round of 16 match against Algeria after catching a flu that swept through the team, affecting a third of the players.

While most of his team mates quickly recovered, Hummels developed a high fever that took him days to get over it and was unsure whether he would even start against the French on a steaming hot day in Rio.

Now the 25-year-old, who is playing in his first World Cup, has established himself as an integral part of the German defense that he hopes will go and win the tournament.

"I guess we're playing the kind of football that will give us the chance to win," he said.

"We know France is among the top teams, so it was certainly not a walk in the park.

"It was not a perfect match but it was a pretty good match and I think we deserved to go on."