Any hopes of success for British women at Melbourne Park dissipated inside the first three hours after Robson was humbled 6-3 6-0 by Kirsten Flipkens and Watson lost 7-5 3-6 6-3 to Daniela Hantuchova.
Robson, who had been forced to withdraw from the warm-up Hobart International tournament with a wrist injury last week refused to blame that for her loss on Monday.
It was an undoubtedly disappointing performance from Robson who was dumped out in 50 minutes.
"She just played better than me," Robson told reporters of her loss to Flipkens. "I don't think I ever really got into a rhythm at all.
"I wasn't really able to deal with her slice that well.
"I definitely expected to play better, but, you know, it happens."
Robson and Watson were the only two British women to make the main singles draw at Melbourne Park, with none involved in the doubles or mixed doubles.
Watson, in contrast, made a better fist of her encounter but was disappointed not to push on having forced her way back into the match having fought back from a set down as her opponent raced into a 4-1 lead in the decider.
"I felt I was close throughout the match," said Watson.
"I started slow in the third set - I should have got up while she went to the bathroom [before the final set] and kept moving - but I had plenty of chances and didn't take them."
The nation's remaining hopes in singles of the year's opening grand slam now rest with world number four Murray.
Last year's beaten finalist, however, is still recovering from back surgery and has already moved to dampen down expectations of his progress at the tournament.
Murray, who meets Japan's Go Soeda in the first round on Tuesday, has played two competitive matches since his surgery, thumping a local in the first round in Doha before he lost to Florian Mayer in the second.
"I still obviously want and try and keep winning as much as possible. That's always been the goal," Murray said before the tournament began.
"If somehow I can work my way into the tournament, feel a little bit better every day, then I might start to raise those expectations.
"But for now they're not going to be obviously as high as they were the last few years."