Andy rues missed chances in Beijing

The Scot spoke out after crashing from the men's doubles tournament in Beijing with brother Jamie - just days after a shock first-round loss in the singles. "I didn't prepare as well as I should have done. It was unprofessional and something I need to learn from," he said.

Andy had high hopes of Olympic success after winning his first Masters Series event, in Cincinnati. However, he made a mockery of pre-tournament medal predictions by losing 7-6, 6-4 to Chinese Taipei's world number 77, Yen-Hsun Lu.

He then paired up with Jamie, also an RBS ambassador, to beat Canada's Daniel Nestor and Frederic Niemeyer in three sets. But their doubles run ended in the next round with a chastening 6-1, 6-3 defeat to French pair Arnaud Clement and Michael Llodra in just 66 minutes.

"I found out the day after my singles match I'd lost four and a half kilos since I arrived here," said Andy. "I'll have to make sure it doesn't happen again because I think I'm playing really well right now, the US Open is my favourite tournament and I believe I can do really well there," he said.

"Ideally I'd have liked to have got here earlier but I didn't because I played very well in Cincinnati. Normally at each tournament I weigh myself right at the start and I should have checked that as soon as I got here instead of the day after my match."

Andy also admitted that he and his brother had disappointed as a doubles pairing, and would avoid making the same mistake in London in four years time. "We didn't serve particularly well or return well and it was always going to be difficult if you can't put any pressure on them," he said.

"After being a part of the Olympics for the first time and seeing what it means when the athletes win medals, and how big a deal it is, you realise how much you want to do well and sometimes you want it a bit too much and don't play so well.

"Next time we will be playing at home on one of our best surfaces and will have a lot more experience."