Knock Someone Off His Perch Meaning

(idiomatic) To defeat or overcome someone who was in a dominant position.

Example: 2004 September 7, “Singh on top of the world”[1], The Guardian:
  Tiger Woods has been knocked off his perch as the No1 player in the world after Vijay Singh beat him in the Deutsche Bank Open last night.
2005 May 16, The Associated Press, “Kanaan Wins Indy Pole; Patrick Settles for Fourth”[2], New York Times:
  He was the third qualifier of the day and posted a 4-lap, 10-mile qualifying average of 227.566 miles an hour on the two-and-a-half-mile oval, then had to wait through nearly six hours while other drivers tried to knock him off his perch.
2011 July 4, Alistair Magowan quoting Kelly Smith, “Women's World Cup: England out to dethrone Germany”[3], BBC Sport:
  "It would be nice to knock the Germans off their perch, with them winning the last European Championship and the World Cup."