All in all, I think this 'treatment of the ball' storm may very well be teacup based.

England coach Trevor Bayliss is currently being interviewed on BT Sport and says he spoke to the umpires once he saw the headlines in the Australian media and they told him there was nothing to worry about.

Full reaction to follow.

Glenn McGrath
Ex-Australia pace bowler on BBC Test Match Special

Maybe because of the difference in the time it started reverse swinging for England, they have started looking for something.

Whether Jimmy Anderson was just brushing something off around that quarter seam, from the footage I saw, you can't make out if he was doing something wrong or what he was doing.

If you start working around the quarter seam and open it up or make it soft, whether that does assist I am not sure but there is potential there.

You want reverse swing but it is about how you do it. The rule states you are not allowed to change the ball by doing something externally to it, something that is not natural.

There are ways you can get reverse swing within the laws.

It has got people talking, especially other former Australia players now working as pundits who have said James Anderson might need to explain his actions.

Having just seen it again, it looks like Anderson is trying to press down a loose flap or a raised part of the shiny side of the ball. Stuart Broad then also tries to do the same, while talking to the umpires about the state of the ball.

It's also crucially the shiny side - not a side England would be wanting to alter, given the aim is to get the ball swinging. They want that side as smooth as possible.

Image source, EPA

Here is what Shane Warne said on Australian TV when he saw the footage of James Anderson pressing his thumb against the ball...

"I'm not sure you are allowed to use your fingernail there," Warne said on Nine's Wide World of Sports broadcast.

"If you are going to touch the ball at all, it's not just shining it, you want to do it right in front of the umpire so they know there is nothing untoward going on. But I'm not sure that Jimmy Anderson ... this might get some people talking."

Graeme Swann
Ex-England spinner on BBC Test Match Special

It is ridiculous. It has annoyed me. The people who are making the story should know better. How you can use the back of your nail to push a bit of leather down on the shiny side and be accused of ball tampering is beyond me.

It is because it is a slow news day and England are in a strong position.

The official word from the match referee is that there has been no report of ball tampering.

However, both sides have been spoken to about deliberately throwing the ball in on the bounce, in an attempt to scuff it up and induce reverse swing.

Michael Vaughan
Ex-England captain on BBC Test Match Special

It looks to me that Jimmy Anderson has got the ball in his hand and has just tried to push down a flap on the shiny side down to make sure it is smooth. He is not scratching it. He is polishing it to make it as smooth as possible.

If it was the other side of the ball, the rough side, it might be a problem but he wouldn't be doing that to the shiny side.

From what I have seen I don't think there is a great deal in it.

Anderson was also pressing his thumb into the shiny side of the ball - not the side England would want scuffed up if they were looking for swing.

There are also pictures of Stuart Broad trying to smooth down part of the surface of the ball, in full view and under the guidance of the umpires.

It looked like a flap of leather had come loose or perhaps swollen in the wet conditions and England were trying to rectify it.

Image source, EPA

Right, so that's the state of the game. But there is a bit of a storm brewing in Melbourne, and not just the literal one.

Several Australian media outlets have been asking questions over England's treatment of the ball today.

TV stations are showing footage of James Anderson pressing the edge of his thumb into the shiny side of the ball, sparking accusations from some of ball tampering.

The umpires did have a word with Joe Root earlier - but that was to do with England throwing in on the half-volley to try and hasten the scuffing up of the ball, which can help to produce reverse swing.

It's a tactic that's been used by both sides during the Test and isn't classed as ball tampering.

Ed Smith
Ex-England batsman on BBC Test Match Special

England's bowling has been pretty good. On this pitch they have been able to have more defensive plans and pack the field in front of square, get reverse swing and bowl straight.

It is not a pitch where you are going to be able to blow a side away.

Image source, Reuters

Image source, Getty Images

Rain has brought an early end to day four at the MCG. Australia are 103-2, trailing England by 61 runs.

James Anderson was caught at short leg from the first ball of the day, ensuring that Alastair Cook carried his bat with a sublime 244 not out as England ended on 491, a lead of 164.

Australia were looking good in reply until Cameron Bancroft chopped on and Usman Khawaja edged Anderson behind, leaving the hosts on 65-2.

But David Warner, Steve Smith and the rain have all frustrated England since, the Aussie batsmen mainly looking to occupy the crease rather than scoring with any fluency.

After an earlier 30-minute delay, the drizzle returned at around 04:00 GMT and got heavier, finally resulting in play being called off.

Michael Vaughan
Ex-England captain on BBC Test Match Special

England have all the cards going into the last day but they will have to take every opportunity.

As a result of the rain delays today, day five will start half an hour early at 23:00 GMT.

Image source, Reuters

Double sigh. That's that. Rain ends play on day four at the MCG.

The hosts are 103-2, trailing England by 61 runs, with David Warner 40 not out and skipper Steve Smith unbeaten on 25.

There has been no play since shortly after 04:00 GMT and there was another 30-minute delay earlier on in the second session.

Cameron Bancroft and Usman Khawaja were the two Aussie wickets to fall, after James Anderson was out to the first ball of the day, leaving Alastair Cook unbeaten on 244 and England 491 all out.

It's now raining in Manchester too.

Sigh.

Glenn McGrath
Ex-Australia pace bowler on BBC Test Match Special

England won't be too disappointed about not getting out there today. The one thing that negates reverse swing is moisture.

With all of the moisture out there now it would be doubly hard to get reverse swing.

That goes against your 5-0 prediction, Glenn!

And the former tormentor-in-chief has more reasons to be cheerful for the tourists...

Glenn McGrath
Ex-Australia pace bowler on BBC Test Match Special

Only one team can win from here and that is England if they come out in the morning get a couple of wickets.

If England break this partnership before Australia get past their total then they are in with a real shot.

Image source, AFP

Despite this frustration, there are some pros to take from this rain delay for England.

It now pretty much eliminates any chance of them losing the Test. OK, they would have had to go some to throw this one away but England have had their share of horror collapses down under before.

It also allows Joe Root and his bowlers to go all-out attack tomorrow. I can't see David Warner and Steve Smith suddenly putting on a flurry of runs to get past England and set them a target. They set their stall out with occupying the crease today.