Sri Lanka took an unbeatable 3-0 lead over a depleted England side in their five-match One-day series on Saturday and off the field the news was equally bleak.
Vaughan, who has not represented his country this year after an operation on his troublesome right knee, will discuss his options with specialists today after displaying increasing discomfort in recent matches for Yorkshire.
Giles has played no cricket at all this year and he is now scheduled to travel to the United States to seek further advice after surgery on his right hip followed by an operation on his groin.
Neither player seems likely to play any part in the four-Test series against a strong Pakistan side starting next month and both must be serious doubts for the Ashes series against Australia later in the year.
Fast bowler Simon Jones, another key member of the side who regained the Ashes last year, has already been ruled out of the Australia tour after knee surgery and all-rounder Andrew Flintoff has played no part in the current One-day series because of an ankle problem.
''All of our injured players are world class -- Vaughan, Flintoff, Giles and Jones -- and it's going to be a big concern if they don't come back and play this season,'' coach Duncan Fletcher told reporters at the weekend.
''I've adopted an attitude that if they do come back it will be a huge bonus. That's why we've got to go with these young other players to try to get them ready for later on in the winter.'' Fletcher's other problem has been the variable form shown by the ''young other players''.
Essex left-hander Alastair Cook, who has not been selected for the One-day team, confirmed the fine impression he made on debut in India this year in the subsequent drawn Test series against Sri Lanka.
Monty Panesar topped the bowling averages against Sri Lanka and looked the best left-arm spinner to represent England since Phil Edmonds 20 years ago. Unfortunately his fielding, in particular, plus his batting fall well short of the standards attained by Giles.
Pace bowlers Liam Plunkett and Sajid Mahmood have been taken apart by the Sri Lanka batsmen during the One-day series and even Steve Harmison, one Ashes hero who has returned successfully from injury, was unable to bowl a consistent line on Saturday.
England's batsmen have also failed to fire and Andrew Strauss, the third-choice captain after Vaughan and Flintoff, offered no excuses after his team's dismal performance on Saturday.
''We need to take a long, hard look at ourselves,'' Strauss told reporters. ''We haven't been up to international standard.'' Time is now fast running out for England if they are to mount a credible challenge in Australia and at the World Cup in the Caribbean early next year and already last year's Ashes triumph seems something of a mirage.
Since England secured the Ashes at the Oval, they have won two and lost four of their nine Tests. Australia have won 11 out of 12.