South Africa claimed the gold medal in a dramatic lightweight men's four final.

In a thrilling sprint for the line, the South African crew of Matthew Brittain, Lawrence Ndlovu, John Smith, James Thompson edged hosts Great Britain into bronze.

Denmark took the bronze medal.

The Danes held the lead coming into the home stretch, but were reeled in and, with 100 metres remaining, it appeared as if Britain had enough to snatch the gold.

But South Africa clinched the victory with the final stroke of the two kilometre race in a time of six minutes 2.84 seconds.

The top three crews were separated by just three 10ths of a second.

New Zealand's Nathan Cohen and Joseph Sullivan won Olympic gold in the men's double sculls.

World champions Cohen and Sullivan won in six minutes 31.67 seconds ahead of Italy and the Slovenian crew who were looking to reclaim the Olympic title they won 12 years ago in Sydney.

New Zealand and Italy produced strong finishes to overhaul Slovenia and row Britain out of the medals.

The United States retained their Olympic title in the women's eight to continue their dominance of the event.

The USA, five-time world champions and unbeaten since 2006, beat Canada into silver with the Netherlands taking bronze.