(CNN) -- Thomas Mueller celebrated signing a new contract with Bayern Munich by helping the Bundesliga champions to win the pre-season German Supercup clash with runners-up Schalke on Saturday.
The 20-year-old, a revelation for Germany at the 2010 World Cup after scoring five goals, broke the deadlock in the second half in Augsburg before Miroslav Klose sealed a 2-0 win.
Before the match, he agreed a two-year extension to his previous deal, which was due to expire in 2013.
"A dream has come true for me, and not just in the course of last season," Mueller, who was joint top scorer in South Africa and also named best young player, told the Bayern website.
"I come from Bavaria, and FC Bayern is my club. I'm delighted that I'll continue to wear a Bayern shirt for the next five years."
Bayern lost 3-1 to Schalke last week in the Liga Total Cup friendly event, as coach Louis Van Gaal fielded several reserve players.
But the Dutchman included six World Cup stars -- minus the injured Arjen Robben -- in a traditional pre-season fixture between league and cup winners which has been reinstated on the calendar after a 14-year absence.
Schalke coach Felix Magath fielded his marquee signing, former Real Madrid striker Raul.
Bayern, who also won the German Cup last season as well as reaching the final of the UEFA Champions League, took the lead in the 75th minute.
Mueller slotted into the empty net when veteran striker Klose put the ball past onrushing goalkeeper Manuel Neuer.
Klose, who scored four goals at the World Cup to move second in the all-time scorers list with Gerd Mueller, doubled the lead from close range six minutes later after Ivica Olic beat Schalke's new Spanish defender Sergio Escudero and provided the assist.
Bayern begin the new Bundesliga season at home to the 2009 champions Wolfsburg on August 20.