BEIJING, Aug 17 (Reuters) - South Korea came back from a goal down to beat Belgium 3-1 in a pool A game that turned on two contested decisions on Sunday to stay in contention for a semi-final spot in men's Olympic hockey.

In the other pool Britain rallied to draw 1-1 with Canada, but the result was unlikely to be enough to keep their medal prospects alive.

Asian Games champions Korea took their tally to seven points with a match left against Spain, unbeaten in three games. Spain play Germany, shaken after two draws, later on Sunday in a match that could determine the qualifiers from that pool.

"In the second half Belgium played poorly and we played better," Korea coach Jun Myung Cho told Reuters. "We have improved with every match."

Gutsy Belgium, who held world number two Germany to a 1-1 draw, went ahead in the 20th minute through a remarkable goal by Jerome Dekeyser.

They had another goal disallowed, however, before South Korea equalised through Sik Hyo You after Seong Eun Hong set it up for him. Belgium contested the score, but it was given the nod by the video umpire.

"It was 1-0 for us and would have been 2-0, it was definitely a goal but it was annulled. Why, I don't know," Belgium captain Loic Vandeweghe told Reuters. "Then in the second half they scored a goal, but it was a fault but was given."

South Korea scored two more quick goals to take control of the match.

Canada went ahead through an opportunistic goal by Ken Pereira in the 47th minute, when Britain were down to 10 for the second time following a yellow card suspension for James Tindall. Britain equalised through Matt Daly three minutes from time.

"The first 25 minutes we showed enough quality to win it, but I think two pieces of ill-discipline cost us horribly," Britain coach Jason Lee said. "We have got no chance now." (Editing by Alex Richardson) (For more stories visit our multimedia website "2008 Summer Olympics" here; and see our blog at http:/blogs.reuters.com/china)