By Jonathan Agnew
BBC cricket correspondent in India
Sehwag has a wonderful eye and an attacking instinct that, sometimes, lets him down but when he comes off he can quickly transform a match
You could not wish for a more enticing final day than what is on offer in Chennai.
All things considered, it is absolutely fitting that this Test should at least offer the possibility of a dramatic finale and although history suggests that England start the day as narrow favourites, it would be a brave man that writes off India's prospects.
If India get a good start on the final morning, they will have to go for their target.
Wickets in hand at tea will be their aim - and the make-up of their batting line up makes them dangerous.
Gautum Gambhir is in fine form, and although Rahul Dravid has struggled of late, he, Sachin Tendulkar and VVS Laxman are the craftsmen whose job it will be carefully to lay the foundation.
After them come the colourful stroke players, Yuvraj Singh and captain Mahendra Singh Dhoni - indeed, with Harbhajan Singh at number 8, it is difficult to see India blocking out for a draw.
In some ways, England best chance of winning is if India stay in the hunt.
The more conventional avenue to an England win, of course, would be to take a couple of early wickets and then chip away through the remainder with attacking fields and men around the bat.
But if this does not happen, they have the alternative route of India perishing while chasing the runs. That is why England start out as favourites.
However, I thought the tourists rather lost their way in Sunday's afternoon session. Their first priority of course, was to establish their commanding position, and that inevitably took time.
Unfortunately, once Andrew Strauss and Paul Collingwood both reached their hundreds (Strauss' second century of the match), they promptly got out, disrupting their rhythm.
Andrew Flintoff fell almost immediately, and the flow of runs dried up to the extent that only 57 were added between lunch and tea.
The trouble was that their initiative was lost, too - and this was compounded by Virender Sehwag's brilliant and outrageous assault.
The only man I have seen bat like this was Wayne Larkins who, like Sehwag, preyed on width outside the off stump.
Sehwag has a wonderful eye and an attacking instinct that, sometimes, lets him down but when he comes off he can quickly transform a match.
Whether his 68 ball 83 manages to do that, we can only wait to see but all of us who were lucky enough to watch his innings were mighty grateful for it.