Former champions Australia produced a stunning fightback to defeat South Korea 5-4 in their opening match of the Olympic women’s hockey here on Sunday. The Hockeyroos, trailing 1-4 at half-time, pumped in four goals in the second session to secure full points in a group ‘A’ match played in heavy evening rain at the Olympic Green hockey stadium. China, gold medallists at the Asian Games in Qatar two years ago, blanked Spain 3-0 in a pool ‘A’ match watched by some 5,000 home fans. Japan, who won the Asian Games silver behind China, warded off a spirited challenge from New Zealand before winning 2-1 in pool ‘B’. The unheralded USA girls justified pre-Olympic predictions that this could be anyone’s tournament by holding world number two and title contenders Argentina to a 2-2 draw in another pool ‘B’ match.