Two of Britain's top Olympic gold medal prospects must overcome strong Australian challenges at the Rowing World Cup on Sunday.

The British men's four, unbeaten heading into Munich, were edged out by Australia for first place in Saturday's semi-finals.

World champions Katherine Grainger and Anna Watkins remain unbeaten going into the women's double final.

However, Australia's Kim Crow and Brooke Pratley qualified fastest.

Crow and Pratley will race the Britons for the first time on Sunday. The Australians are making their 2012 debut after Pratley missed the start of the season through injury. In her absence, Crow raced in the single and qualified for an Olympic place in that discipline.

Pete Reed's guide to the Team GB's coxless four

Australian selectors must decide after Munich  - the final competition before London - whether to keep the duo in the double scull at the Olympics and forego a place in the single, or split them up and draft in a replacement alongside Pratley.

Andrew Triggs Hodge, Pete Reed, Tom James and Alex Gregory managed to hold off the Australian four's challenge in Lucerne last month but there are signs that the gap is closing. Sunday's final will be the true test.

"Let's see what happens tomorrow," said Triggs Hodge. "We had a good race today, better than yesterday, and every race feels like part of a progression."

Great Britain will have 14 finalists across 12 Olympic class events in Munich following Saturday's semi-finals.

Lightweight double scull Olympic and world champions Zac Purchase and Mark Hunter are looking to recover from finishing sixth last time out, and showed positive signs as they won their semi.

Purchase and Hunter held off the impressive new French pairing of Stany Delayre and Jeremie Azou, winners of the previous World Cup regatta, and will face them again on Sunday along with long-time rivals Storm Uru and Peter Taylor of New Zealand.

Great Britain's Helen Glover and Heather Stanning, unbeaten this season in the women's pair, saw off Romania to win their heat on Friday and qualify directly for Sunday's final, where they will face world champions Juliette Haigh and Rebecca Scown of New Zealand among others.

Team GB named 48 rowers in the squad for London last week, with four more to be added, and Munich provides one more chance for those in the balance to put their case.

The men's and women's eights are still to have their crews confirmed.

In the Paralympic class finals, Britain's world champion mixed adaptive coxed four - Pam Relph, Naomi Riches, Dave Smith, James Roe and cox Lily van den Broecke - won gold after coming from behind to beat Germany in a nail-biting finish.

"That was definitely one of our best performances," said Roe.

"We have never had to come from behind with 250m to go. Obviously, we have practised that in training but we've never had to use it."

Andy Houghton won bronze in the arms-only single scull final - but he was not satisfied.

"I'm really disappointed with that," said Houghton, who had leg muscle spasms throughout.

"I just wanted a good run at it today as my times in training are comparable with these guys, the medallists."