Match opposition! (5)
I believe the answer is:
rival
I believe this is a double definition.
'match' is the first definition.
('rival' can be a synonym of 'match')
'opposition' is the second definition.
(thesaurus)
(Other definitions for rival that I've seen before include "Contestant you hope to defeat" , "Contender" , "Competing opponent" , "Someone you hope to defeat" , "Compete with" .)