Jos Buttler is confident England have put themselves in position to clinch series victory over India in the fourth Specsavers Test at Southampton.

Buttler's battling half-century helped the hosts muster a second-innings 260 for eight, to leave India facing a target of at least 234 to level up at 2-2 over the last two days.

England's wicketkeeper also put up a staunch defence of captain Joe Root's unexpected decision to drop back down to number four here, with Moeen Ali pushed up to little avail above him.

Before the vice-captain was required to speak on that topic, however, he made it clear England fancy their chances of taking an unassailable 3-1 lead on a pitch which has begun to favour spin early.

Asked if England can limit India to under 250, Buttler said: "Yes, definitely.

"You've seen the wear and tear in the wicket - even in the first innings as well, there was quite a bit of rough outside the right-hander's off-stump.

"That's promising for Moeen and Adil (Rashid) - and with the seamers, we've seen a bit of variable bounce."

As for Root's surprise switch back down one position, for the first time this summer, Buttler added: "It was just a pure tactical decision - Moeen has been in such fantastic form for the last couple of weeks, and bats at number three for Worcestershire."

It did not work for the all-rounder here, but Root fared better until he was run out for 48.

Buttler declined to confirm whether it is likely to be a long-term rejig.

"I'm not sure, moving forward, what will happen - but tactically for today, it just felt like the right decision," he said.

"For a world-class player like Joe, I don't think it affects him too much.

"At the minute, we're just trying to work out the best combination.

"The best teams in the world, you could turn up every week and write that side out. Stability is a key pillar in a lot of successful teams."

Another controversial positional change here, enforced because of Jonny Bairstow's broken finger, has been Buttler's own return to keeping wicket in Tests.

But he insists there are no hard feelings about the situation.

"It's not been a problem at all," he said.

"Not at all from my angle, and not from Jonny's either."

Bairstow has managed just six runs here as a specialist batsman and was out just after lunch for his second golden duck in three innings, sparking suggestions among some pundits that the move has not gone down well with him.

Buttler said: "Obviously Jonny's not fit to keep wicket in this match, which is frustrating for him because he's been fantastic for the last few years.

"I'm not fussed.

"From a few months ago, to even be in the Test match side is fantastic - so gloves on or not, it doesn't matter."

It was unsurprising to hear from the India camp that they view pitch conditions - and therefore their prospects - differently.

First-innings centurion Cheteshwar Pujara disputed the suggestion that the tourists had a taxing time in the field, and added they will be very much at home on a surface increasingly sub-continental in nature.

"I don't think it was a tough day for us," he said.

"The pitch has slowed down a bit, and it looks like it's slightly easier to bat.

"We have a lot of experience playing in such conditions back home.

"All the batsmen realise what they need to do."