Stewart: If Hamilton finishes ahead of Vettel on Sunday, the Championship is over. Ferrari need a 1-2 this weekend.
Ben Berwick: Pretty terrifying incident. Tracks need to make sure these covers are secure.
AFP/Getty ImagesCopyright: AFP/Getty Images
Post update
A delayed start to first practice and a abrupt finish to second practice.
A disrupted day in which Ferrari showed promising pace but Mercedes appear to have lots of work to do.
FP2 - the rest
11) Palmer
12) Massa
13) Vandoorne
14) Stroll
15) Gasly
16) Sainz
17) Grosjean
18) Magnussen
19) Wehrlein
20) Ericsson
FP2 top 10
1) Vettel 1:31.261
2) Raikkonen +0.604
3) Ricciardo +0.838
4) Verstappen +0.848
5) Alonso +1.303
6) Hamilton +1.416
7) Bottas +1.459
8) Perez +1.601
9) Hulkenberg +1.799
10 Ocon +1.835
'The next thing I knew there was no tyre'
Romain Grosjean has just been speaking to Sky Sports. He's actually got a big smile on his face as he says: "I am good. I am fine, that is the most important thing.
"I have just seen the footage. I was on the racing line and had a big hit on my rear right. The next thing I knew there was no tyre there anymore and I was spinning."
SESSION WILL NOT BE RESTARTED
There's clearly too much work to be done to sort that exposed drain and race control have confirmed the session will not be restarted.
Post update
There's 11 minutes left but I can't see us getting any more running done in this session. Race director Charlie Whiting has just emerged from a safety car to inspect the hole. It's a big hole as well.
Exceptionally dangerous. You can see that cover sticking up in the air and we are seeing the wheel of the Haas, absolutely shredded.
Post update
Looking at replays, it seems a drain cover came loose on the inside of the kerbing after Valtteri Bottas and Kimi Raikkonen ran over it. Then the unfortunate Romain Grosjean came round, hit the drain cover and it obliterated his right rear.
Red flag
Romain Grosjean is into the barrier!
He lost control of his Haas, there's debris on the track which appears to have come from his right rear.
Fortunately the Frenchman appears OK as he climbs out of the car.
Post update
Carlos Sainz has been having all sorts of problems today. He had earlier called his Toro Rosso "undriveable" and now says he has no power on the main straight.
Live Reporting
Gary Rose
All times stated are UK
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Right that's it from us. We'll be back bright and early on Saturday morning for final practice and then qualifying.
Join us from 06:30 BST tomorrow. See you then.
Post update
Missed second practice? Catch up by reading Andrew Benson's report here.
Predict who will top qualifying in Sepang
Fancy being brave and making an early prediction for qualifying? Head here to predict the top three.
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Stewart: If Hamilton finishes ahead of Vettel on Sunday, the Championship is over. Ferrari need a 1-2 this weekend.
Ben Berwick: Pretty terrifying incident. Tracks need to make sure these covers are secure.
Post update
A delayed start to first practice and a abrupt finish to second practice.
A disrupted day in which Ferrari showed promising pace but Mercedes appear to have lots of work to do.
FP2 - the rest
11) Palmer
12) Massa
13) Vandoorne
14) Stroll
15) Gasly
16) Sainz
17) Grosjean
18) Magnussen
19) Wehrlein
20) Ericsson
FP2 top 10
1) Vettel 1:31.261
2) Raikkonen +0.604
3) Ricciardo +0.838
4) Verstappen +0.848
5) Alonso +1.303
6) Hamilton +1.416
7) Bottas +1.459
8) Perez +1.601
9) Hulkenberg +1.799
10 Ocon +1.835
'The next thing I knew there was no tyre'
Romain Grosjean has just been speaking to Sky Sports. He's actually got a big smile on his face as he says: "I am good. I am fine, that is the most important thing.
"I have just seen the footage. I was on the racing line and had a big hit on my rear right. The next thing I knew there was no tyre there anymore and I was spinning."
SESSION WILL NOT BE RESTARTED
There's clearly too much work to be done to sort that exposed drain and race control have confirmed the session will not be restarted.
Post update
There's 11 minutes left but I can't see us getting any more running done in this session. Race director Charlie Whiting has just emerged from a safety car to inspect the hole. It's a big hole as well.
Post update
Post update
Mark Gallagher
BBC Radio 5 live Formula 1 analyst
Exceptionally dangerous. You can see that cover sticking up in the air and we are seeing the wheel of the Haas, absolutely shredded.
Post update
Looking at replays, it seems a drain cover came loose on the inside of the kerbing after Valtteri Bottas and Kimi Raikkonen ran over it. Then the unfortunate Romain Grosjean came round, hit the drain cover and it obliterated his right rear.
Red flag
Romain Grosjean is into the barrier!
He lost control of his Haas, there's debris on the track which appears to have come from his right rear.
Fortunately the Frenchman appears OK as he climbs out of the car.
Post update
Carlos Sainz has been having all sorts of problems today. He had earlier called his Toro Rosso "undriveable" and now says he has no power on the main straight.
"Box, box," he is told.
Post update
Post update
We're at the end of the qualifying sims. Here's the top 10:
1) Vettel 1:31.261
2) Raikkonen +0.604
3) Ricciardo +0.838
4) Verstappen +0.848
5) Alonso +1.303
6) Hamilton +1.416
7) Bottas +1.459
8) Perez +1.601
9) Hulkenberg +1.799
10 Ocon +1.835
Get involved #bbcf1
Chris Marsh: Did Mercedes bring the 2016 car this weekend? Good of them to give Ferrari a fighting chance.
Post update
Lewis Hamilton heads back into the pits, gets out of his Mercedes and leaves his crew to work on his car.
Early doors, but things looking good for Ferrari.
Thinking caps on