The middle-order batsman is likely to require surgery for the torn ligament in his left knee. Andrew Leipus, former physio of the Indian team, has stated that the recovery process generally takes four months and Yuvraj will be "touch-and-go" for the World Cup if he indeed requires surgery. A final assessment with BCCI Dr. Anant Joshi is scheduled for November 13.
Yuvraj has been India's best one-day batsman over the past year and he has matured immensely of late. His absence in the middle-order means that Raina, Mongia and Kaif will have to step up big time and that the services of VVS Laxman may be called upon. Yuvraj is also likely to miss the tests in South Africa, which will give Kaif an opportunity to bat at #6 whenever India (sensibly) plays six specialist batsmen.
Let's hope for a speedy recovery.