China hasn't got any real experience fighting wars. And Russia's grand military failed to defeat Afghanistan in the 19(70s?).
The only military really to have proven its worth against another modern power is the UK in the Falklands War, 1982. The invasion of Iraq was hardly fair, but the Falklands war saw the British outnumbered on paper pretty heavily.
EDIT: Thinking about Yuogslavia etc, they have all been really unbalanced wars.