England skipper Michael Vaughan and pace bowler Simon Jones have been ruled out of the first Test against India, which starts in Nagpur on Wednesday.
Jones receives treatment from the team doctor
Both will fly home to see specialists about knee problems and are doubts for the remaining Tests and one-dayers.
All-rounder Andrew Flintoff will lead England in a Test for the first time.
Vaughan is struggling with the right knee problem he had surgery for in December, while Jones twisted his left knee in a practice session on Monday.
The Welshman had been trying to prove his fitness following an ankle problem but crumpled to the ground after pulling up in his delivery stride and a hospital scan revealed minor cartilage damage.
The only crumb of comfort for Jones is it is not the same knee in which he suffered severe ligament damage during the first Test of the last Ashes tour to Australia in 2002.
His absence could mean another chance for seamer Liam Plunkett but he is also doubtful with a bruised heel.
The injuries to Vaughan and Jones add to a catalogue of setbacks that England have suffered ahead of the series in India:
- 7 February - Ashley Giles withdraws from tour after failing to recover from back surgery.
- 22 February - Shaun Udal, Simon Jones, Monty Panesar and Ian Blackwell all go down with a stomach bug on the eve of England's second practice match, while Paul Collingwood's back injury rules him out altogether.
- 23 February - Vaughan withdraws from warm-up match and Kevin Pietersen later retires hurt with a back problem.
- 25 February - Vice-captain Marcus Trescothick announces he is leaving the tour for undisclosed personal reasons.
- 27 February - Jones collapses with a twisted knee before it is announced Vaughan is flying home for treatment on a recurring knee injury.
England chairman of selectors David Graveney admitted he had never seen a worse injury crisis.
"I've never known a combination of injury and illness to such a degree," he told BBC Radio Five Live.
Vaughan walks off after losing his fitness battle
"We've obviously had massive problems but these things happen and we're not just going to down tools and not compete on Wednesday.
"We will put on the park 11 people who are proud to represent their country and compete against India."
Former England Under-19 captain Alastair Cook is almost certain to win his first cap as Andrew Strauss's new opening partner.
Cook was summoned from the England A tour in the West Indies along with fast bowler James Anderson, while batsman Owais Shah is due to arrive later on Monday.
Vaughan missed the end of the tour to Pakistan to undergo surgery before Christmas.
But Graveney disputed suggestions players were rushed back into the side too soon.
"We select our teams on the best possible medical advice," he added.
"Vaughany played in the first (tour) game, didn't have a problem and the situation has recurred since then."