I think I read somewhere that Tiwary got injured again recently and even had to miss out on a domestic match. But they should have gone with Rayudu. He was in sterling form in the recent domestic games. Rayudu is another guy who is test material. We have enough test materials waiting in the wings like Tiwary, Rayudu, Rahane, etc.
But I have a feeling that Rahane will open with Vijay in Delhi. They tried to replace Dhawan with Gambhir, but with Gambhir having jaundice, they seem to have decided to have Rahane as opener, and give Rahane's middle order spot to Raina. I wish this scenario is what is the right one. I however fear that with too much talk going on about Rahane's struggles to get into the test side, when he eventually lands up there, he could be in for a failure and that can trouble him if he is not strong enough