Australia's only hope of holding onto their number one ranking is if they win their final Test in Colombo on Saturday, having already lost the series (which Sri Lanka lead 2-0).

They also require a draw or a Pakistan victory at The Oval, and India to fail to win both of their games, if the Aussies are to keep top spot.

It's fairly simple for India, who will go top of the ICC Test rankings if they win both remaining Tests in the Caribbean for a 3-0 series win. No-one can catch them in that scenario.

But if they win one and draw one, for a 2-0 series win, they are guaranteed to be overtaken by the winner of this England-Pakistan Test (or overtaken by England if it's a draw).

BBC Sport's Steve Marshall: So Asad Shafiq gets a pair at Edgbaston and is rewarded by being promoted from six to three. Wow!

England will go top of the ICC Test rankings if...

• They beat Pakistan at The Oval for a 3-1 series win, and India do not win both of their remaining Tests in the West Indies.
• They draw at The Oval to win the series 2-1, India do not win both remaining Windies Tests, and Australia do not win the final Test in Sri Lanka.

In fact, a 2-1 win for England, 2-0 win for India and 2-0 win for Sri Lanka would see England, India and Australia level on 110 points - with England on top by the slenderest of margins.

Right, stand by your beds, I'm going to try to explain what England (and the other teams) need to do to get to number one...

With Adil Rashid released to play for Yorkshire at Glamorgan tonight, Jake Ball is the official 12th man, but he's joined by an array of others. Freddie van den Burgh, Ryan Patel and Chris Jones are Surrey youngsters, but also carrying the drinks will be Stephen Croft (we assume the Lancashire one who spells his name with a "v", rather than his namesake the Bishop of Oxford, though that could be amusing).

If you know of any other Stephen/Steven Crofts, please get in touch...

BBC Weather's Darren Bett: "It does look very promising for this Test. We'll have a lot of cloud cover. There's still a chance of spits and spots from the north. The cloud will thin in the afternoon. Tomorrow it will be dry with more sunshine and it will be warmer as well. The temperature could get up to 26 degrees."

Michael Vaughan
Ex-England captain on BBC Test Match Special

I'm surprised Rahat Ali is the one to miss out. He produced some wonderful spells at Edgbaston. I'm not surprised Hafeez has been left out.

You read that right - Pakistan have had a bit of a shuffle of their batting order. Azhar Ali is promoted from number three to open, Asad Shafiq rises from six to three, and debutant Iftikhar Ahmed (below) comes in at six, rather than opening as some had anticipated.

Image source, Getty Images

England: Alastair Cook (capt), Alex Hales, Joe Root, James Vince, Gary Ballance, Jonny Bairstow (wk), Moeen Ali, Chris Woakes, Stuart Broad, Steven Finn, James Anderson.

Pakistan: Azhar Ali, Sami Aslam, Asad Shafiq, Younus Khan, Misbah-ul-Haq (capt), Iftikhar Ahmed, Sarfraz Ahmed (wk), Wahab Riaz, Yasir Shah, Mohammad Amir, Sohail Khan.

Umpires: Bruce Oxenford, Marais Erasmus

TV umpire: Joel Wilson; Match referee: Sir Richie Richardson.

Image source, Getty Images

Pakistan captain Misbah-ul-Haq on TMS: "We were also planning to bat first, as spinners come into play later on at The Oval. You never know in cricket, the first two hours are always important if you can get something out of the pitch.

"We make two changes - Mohammad Hafeez and Rahat Ali are not playing, Iftikhar Ahmed and Wahab Riaz are in."

England captain Alastair Cook: "We'll have a bat first. We had a long hard thought about it. The wickets here are good wickets. You're always tempted with green grass to bowl first, and the first hour will be hard work. But it will turn on days four five, especially with the sun coming out. It might reverse in days four or five. We've got to focus on today and getting through the first hour and session.

"We wanted to keep the team's balance. It's tough for Adil Rashid. But if he gets a go he's got to make the most of it."

MIsbah-ul-Haq calls heads. It's tails. And Captain Cook elects to bat. England, as we expected, will be unchanged.

Ed Smith
Ex-England batsman on BBC Test Match Special

I would be very tempted to have a bowl. When is the best time to bowl in a match? I'd be very surprised if it's not today on day one.

Captains walking out. Conditions uncertain, pitch looks good, but it's overcast and the best bowling conditions of the match might be right now. Bat or bowl, bat or bowl?

Michael Vaughan
Ex-England captain on BBC Test Match Special

For Pakistan it's a tricky decision. The way Pakistan can win is to bat first in any conditions. For the way that they play, with Yasir Shah, with the way they won at Lord's, is to put runs on the board.

BBC Test Match Special

TMS are up and running. If we've not already mentioned it, the series is still on the line here - England, having come from behind, are 2-1 up with one game still to play. The toss is imminent. Bat or bowl, bat or bowl?

Image source, ICC

Here's how the standings are at the moment. But by using the ICC's rankings predictor,, external you can see how they can drastically change as three simultaneous Test matches take place.

As well as England v Pakistan, we're already two days into West Indies v India, while Sri Lanka v Australia (final Test of three) starts on Saturday. Any one of India, England or Pakistan could dethrone Australia.

I'll run through the permutations in a little more detail between now and the start of play. For now, get your wireless ready as Test Match Special will be on air from 10:25 BST. And we'll be bringing you the toss shortly after that.