Complex sentence: In August 2013, They became world champions after winning 2013 BWF World Championships defeated the Danes pair Mathias Boe and Carsten Mogensen 21-13,23-21, withouth losing any single game to all of their opponents since the first round.
Split into simpler sentences: In August 2013, They became world champions after winning 2013 BWF World Championships defeated the Danes pair Mathias Boe and Carsten Mogensen 21-13,23-21. To make it more perfect, during the tournament, they didn't lose any single game to all of their opponents since the first round.