India v England: Keaton Jennings showed an excellent attitude in debut hundred

In making a hundred on day one of the fourth Test against India, Keaton Jennings showed an excellent attitude for a young man of 24 playing in his first Test innings.

Jennings also demonstrated the way to play on this Mumbai pitch. The surface is deteriorating quite quickly, more so than the three previous pitches in this series, and runs and time at the crease are clearly essential.

He was dropped on nought but he played excellently after that slight lapse. He drives very well, he's tall, stands up and plays straight.

I loved the way he reached his hundred with a reverse-sweep. I know that's a modern batsman's shot but you've still got to have a pretty composed attitude to pull that out when you need four for your first Test hundred. That shows that he's got a pretty strong character as well. It was an excellent start for him.

Jennings and Hameed 'two young players with a lot of promise'

Following Haseeb Hameed's performance in the first three Tests of the series, Jennings' emergence will hopefully enable Joe Root to go back to number four, which is better for all manner of reasons - it splits up him and Alastair Cook, and Root just looks better suited for number four.

I could imagine Hameed opening with Cook and Jennings batting at number three. That already looks a stronger top order. Moeen Ali batting at four is clearly too high, I'd rather see him back down at number eight with Jonny Bairstow and Ben Stokes also coming in a little lower than five and six.

In Jennings and Hameed, we've got two young players with a lot of promise. They look like they could play the game well, not just in terms of technique and ability but in their character too. I like the look of both of them. Even though this has been a difficult tour for England, hopefully it's unearthed a couple of good young players for the future.

'Reckless' shots cost England again

In addition to Jennings, Root was the other batsman who was blameless in getting out, caught at slip off Ravichandran Ashwin for 21.

But I'm sure Cook, Moeen and Bairstow will be disappointed in how they were dismissed.

I know there has been talk about playing positively, and the coach Trevor Bayliss has spoken about this, but I think they have been slightly lured by the Indians talking about England batting too slowly and too defensively.

On this surface run-rates are almost irrelevant because the pitch is deteriorating over time. You have got to nail down that first-innings total that should set you up to win the game.

Alastair Cook was stumped by Parthiv Patel as he moved down the wicket to Ravindra Jadeja

The pitch will never be better than when you have first use of it. To see Moeen slog-sweeping, Bairstow sweeping out into the deep and Cook charging down and getting stumped - that's just reckless. It's not a sensible way to approach batting in these circumstances. When the bowlers are getting help, you don't give them any more.

It's clearly going to be very difficult for England batting on the third or fourth day on this wicket. You've got to make the most of the first chance and three of the five dismissed didn't do that today.

Balancing act to fairly reflect the English system

Keaton Jennings, the son of former South Africa coach Ray Jennings, said he feels "very English" before the fourth Test

The first thing to make clear about Jennings, who was born and brought up in South Africa and captained their under-19s, is that he is eligible to play for England.

What the selectors have to bear in mind, I believe, is that they should pick the best players who are available while at the same time fairly reflecting the English system and giving an incentive to English county cricketers.

I was furious when Darren Pattinson was chosen against South Africa in 2008 because it was totally unnecessary and did a lot of damage to the integrity of the England team selection. There were plenty of fully English bowlers from the English system who could have been picked, rather than an Australian.

The selectors do like the look of Keaton Jennings, ahead of Middlesex's 22-year-old Nick Gubbins. That's the debate - should they have gone for Gubbins first because he has come through the English system or do you go with somebody who has been captain of South Africa's U19s? It's a very difficult debate.

Australia-raised Darren Pattinson had played just 11 first-class matches prior to his surprise England call-up against South Africa at Headingley in 2008

I played county cricket wanting to have the incentive of playing cricket for England. That was very important and if you lose faith in the selection system then county cricket will not do its job. You need to have motivated county cricketers who are going to come through the English system with the target of playing for their country.

What I hear of Gubbins is that he is a very solid fellow and his chance will hopefully come but I can understand the chuntering about Jennings' background. He has an English mother and has served his time because he wanted to play for England - that's different from Pattinson who just happened to be here to play county cricket for Nottinghamshire.

I do think it's not simply a question of the selectors having to pick the best player, full stop. There are other criteria that they must consider, particularly not disincentivising English county cricketers.

400 would still be a good score

England closed day one on 288-5 and there is still batting to come. If the tourists can get 400 then I think that's going to be a good score.

You never know with these pitches, it's done a lot quite quickly so far, perhaps it might not do so much on day two. But the signs are that a score of 400 should put you in a good position.

Jonathan Agnew was speaking to BBC Sport's Alan Jewell