As I said before, we shouldn't be thinking declaration until at least after tea. I think being bowled out is frankly more likely. We haven't even batted 4 full sessions yet, but are leading by 290 at the start of day 3.
First order of business is to push on and get that lead up as big as we can (500+) if possible.
Second order of business is to grind the Indian bowlers into the pitch and see if we can't break Zak for the rest of the tour.
I can't see how Clarke batting on for as long as he can stay upright does anything other than help both of these aims. If we can't knock a demoralised India over in 6.5 sessions with the prospect of some cloud cover to help us swing the ball and a day 4/5 track then we don't deserve to win. I certainly don't want to give them the opportunity to induce a late collapse on day 5 chasing a small target if we give them the chance to bat with say 8 sessions to go and they can grind out a small lead. f**k em. We have the foot on their throat. We use the other foot to kick their head.
