The highs of Lord's have quickly given way to the lows of Headingley, and, as is always the case after heavy defeat, the debate over India's selection leading up to the fourth Test has grown cacophonous. Who should play, who shouldn't, and why? Here are the major questions for India to answer going into The Oval.

Should India play an extra batter?
They were bowled out for 78 on the first day at Headingley, and lost their last eight wickets for 63 on the fourth. While Virat Kohli said after the match that he has "never believed" in having a sixth specialist batter, and that having that batter would be "no guarantee" against such collapses, he has in the past picked combinations that included that extra batter and only four specialist bowlers.

There is a chance that India might be forced to go with six batters anyway, if the knee injury that Ravindra Jadeja suffered at Headingley rules him out of the fourth Test. On this tour, Jadeja has been more of a batting allrounder than a bowling allrounder, with his most telling contributions being his 56 at Trent Bridge and his first-innings 40 at Lord's rather than his tight but mostly nonthreatening bowling, as his output of 15.2 overs per innings and his strike rate of 228.0 would suggest.

If Jadeja is to be replaced, therefore, it's his batting India will probably want to cover before his bowling. But even if he's fit, India might consider playing a sixth batter, given the lack of runs from Ajinkya Rahane (who averages 19.00 in this series) and Rishabh Pant (17.40) in particular.

If they pick a sixth batter, for whatever reason, the obvious choice would be Hanuma Vihari, but there's also the option of shifting KL Rahul - who began the tour as a middle-order option - down the order and picking either Mayank Agarwal or Prithvi Shaw to open alongside Rohit Sharma. Vihari would probably be the likelier choice, given both his status as the next middle-order batter in line, and the utility he brings with his part-time offspin.

Should India replace Rahane?
India could introduce Vihari or another new batter into the team even if they stick to their favoured five-bowler combination, if they leave out Rahane. It would be a big call, since he's their vice-captain, and an experienced hand who has scored runs all over the world. He has only passed 20 once in this series, but that innings, a second-innings 61 at Lord's, played a key role in India winning the Test match. It's not too long ago, moreover, that he made a series-turning hundred at the MCG.

And while Rahane averages only 26.25 since the start of 2020, Cheteshwar Pujara (27.56) and Kohli (24.68) have similar numbers, and these numbers suggest, more than anything else, that India have had to bat in difficult conditions and against strong attacks more often than not. India, therefore, may believe that a significant score may be just around the corner for Rahane, just as it was for Pujara in the second innings at Headingley.

However, it wouldn't be entirely out of character for India to drop Rahane. They have left him and Pujara out in the past when they've felt recent form has demanded it, or if they have noted a technical issue that would be better dealt with in the nets.

Should India bring in Ashwin?
Kohli has maintained throughout this series that the bowling depth offered by a fourth seamer is vital in English conditions. As a result of this, and because of Jadeja's batting ability, R Ashwin has played no part in the series.

The Oval, however, has been the best ground in England for spinners since the start of 2016, going by their collective average of 29.52 here. Just as significantly, it's been the worst ground in the country for fast bowlers, who have a collective average of 32.38.

If Jadeja isn't fit to play, Ashwin is probably likely to come in anyway, as one of four specialist bowlers. But even if Jadeja does play, there is a chance, given these numbers and given the largely warm and dry forecast for London in the week of the Test match, that India will play Ashwin, reverting to a 3-2 bowling combination.

If he plays, Ashwin will come into the game with a lot of confidence, having arguably been India's best bowler in the World Test Championship final against New Zealand in Southampton, and having taken a six-wicket haul in a County Championship game for Surrey at The Oval last month.

What about the seamers?
Given the short gap between the third and fourth Tests, and the workload of a five-Test series, some amount of rotation of the fast bowlers is inevitable, and India could well make a change at The Oval. Ishant Sharma could miss out, given his struggle for rhythm in the third Test, and there is a chance of Shardul Thakur, who played the first Test before missing out at Lord's with a hamstring injury, coming in should India stick with four seamers.

Jasprit Bumrah, Mohammed Siraj and Mohammed Shami have played all three Tests, meanwhile, and while all three have excellent numbers for the series, India could be keeping an eye on their workloads too. Umesh Yadav, who hasn't yet featured in the series, could get a look-in at some point, in case India feel the need to rest and rotate.

Karthik Krishnaswamy is a senior sub-editor at ESPNcricinfo