Postpublished at 08:11 Greenwich Mean Time 5 February 2021
The batsmen take a well deserved unofficial drinks break at the end of the over. Sibley uses a towel to wipe away the sweat in the searing heat.
Kohli is turning back to Bumrah. Danger...
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Root scores century in his 100th Test, off 164 balls
England captain's third ton in three Tests
Opener Sibley also nearing century
First Test, day one, Chennai, England won toss
Callum Matthews
The batsmen take a well deserved unofficial drinks break at the end of the over. Sibley uses a towel to wipe away the sweat in the searing heat.
Kohli is turning back to Bumrah. Danger...
Sibley 48, Root 32
A heart-in-mouth moment as Root clips off his hip. With Virat Kohli lurking at leg slip that's a dangerous shot.
Tea will be at 8:40 GMT, by the way, if you need to squeeze in 20 minutes concentrated home schooling.
Michael Vaughan
Former England captain on the Cricket Social
This pair both need to go on and get three figures. That's why Joe Root was so successful in Sri Lanka because he went on and got those big hundreds.
You don't beat India with 60s and 70s - you beat them with an individual getting 150-200 and 450 as a minimum.
England are in a nice position but you know against this India side, because they've held in nicely, that they are only a couple of wickets away from taking control of the day.
Sibley 48, Root 31
"To the Eng-er-land four more," the Barmy Army sing from their living rooms. Sibley clips the ball to the rope again. He has faced 151 balls and is on the verge of a fifty.
Breaking your collarbone hurts a lot doesn't it? As a kid, I played while unaware I had broken my arm falling off my bike earlier in the day. I didn't last very long.
#bbccricket
Simon Wilcox: Tripped over my own feet chasing a boundary and broke my collarbone. Took a great catch in the next over. Didn't realise it was broken until the next day.
This looks to be a clear plan from this two to up the scoring. Root nails a sweep through mid-wicket to the boundary.
The camera pans to Kohli. He has a little to think about.
Andy Zaltzman
Test Match Special statistician on the Cricket Social
There is a slight curiosity about Chennai and the trends at the ground in Tests this millenium. This is the ninth and the team batting first hasn't won any of them yet (5L, 3D). The most recent one was England's Test in 2016.
India have only batted first in one of those Tests - a rain-affected game against Sri Lanka in 2005.
Sibley 44, Root 26
Errrm. Dom Sibley has just played what I am going to call a slog sweep. Dom Sibley! A slog sweep!
He doesn't get anywhere near the middle of it but gets four.
"Mowed down by a mobility scooter". That one actually made me laugh out loud.
Root is reverse sweeping again. Just a single this time.
Text us on 81111
I had an unfortunate cricket debilitating injury. I was crossing a road when I was struck by a 90-year-old chap in a pimped-up mobility scooter. Mown down in the middle of the road I got my ankle trapped and motorists had to stop to lift the vehicle off me. When the ambulance came to the "road traffic accident" they laughed - with relief I hope?! Stopped me playing a couple of months of village cricket.
Brendan from Warrington
Sibley 40, Root 25
If there are any earplug salesmen reading this then you've missed a tick not getting in touch with England for this winter tour. After the chirp of Niroshan Dickwella they now have the near constant chatter of Risabh Pant behind the stumps.
You could make a fortune.
Root cracks another sweep but picks out Ishant at fine leg. This partnership has not been flowing but effective. The scoring has increased in the last few minutes.
Abhishek Jhunjhunwala
Former IPL batsman on The Cricket Social
India have been pretty decent. They have kept things quiet and haven't let England get off or given them free runs.
They will be looking to dry the runs up so that at some stage Dom Sibley or Joe Root have to take some chances, but both of them have been pretty steady. They are not looking to get quick runs.
There's a long way to go but if England can get on top of Sundar and Nadeem it would be a massive plus.
It wouldn't leave Kohli with many options outside his three main bowlers.
Hello Dominic Sibley!
He skips down the pitch and clips Nadeem through mid-wicket for four. Lovely, lovely shot.
Two players injured in one collision. And a drop. Impressive.
Text us on 81111
Playing for Burley at Parley in the Bournemouth and District League in 1989. I was at long-off, the ball was hit in the air towards the sight screen. I moved across, and set myself. As the ball fell into my hands, I was struck in the ribs by the shoulder of the substantially shorter-than-me long-off, who had ignored my shout of 'Mine!'. I cracked two ribs and long-on fell awkwardly and broke his ankle! The catch went down.
Mark in Somerset
Sibley 35, Root 22
Oh yes! The reverse sweep did for Rory Burns earlier but Joe Root is so much more comfortable playing it.
He nails one behind square on the off side off Sundar. Four runs.
Michael Vaughan
Former England captain on the Cricket Social
Rory Burns will be sat in the changing room now looking at Dom Sibley, who hasn't taken any risks. This England team, for 18 months now, has been about batting long periods of times in the first innings and what Burns will have to do now is work on a pitch that will be doing a damn sight more in the second innings.
He has missed a great opportunity to get a big score and start the series with a big number. I haven't seen him play that shot too many times, I'm sure he'll have been working on it but he just didn't execute it. Even if had executed it and it had gone for four I would have said 'I'm not sure you need to be playing that now'.