Mahaney, ranked 12 places below Dickson, moved up to 13th in the world after his silver-medal performance at the Barcelona Olympics.
Russell Coutts, of New Zealand, and the Australian, Peter Gilmour, earned the other two semi-final places and will square off in a best-of-three match contest for a spot in the finals.
Dickson, ranked No 1 in the world for most of the past four years, secured a semi-final berth on Friday and was under no pressure in Saturday's final day of qualifying. 'We started off with a low pressure day then put the heat on ourselves for the last race against Peter Gilmour,' Dickson, who lost two of three races sailed in winds that built from six to 15 knots, said.
Gilmour's bowman, Marc Walsh, had to be taken to hospital immediately after the final race to have a head gash stitched up after being hit by the boom before the start.
'The first I knew about it was after the finish when he took his hat off and it was covered in blood, but I thought he was a bit lethargic during the race,' Gilmour said.Reuse content