Three or four weeks became five months: Bethell's knee keeps saying no

England's white-ball tour of Australia starts at Optus Stadium on Friday. Jacob Bethell will not play any of it.

He suffered a "setback" in a training session in Perth earlier this week, a scan on his right knee confirmed it, and England have decided he flies back to the UK on Saturday to see a specialist. That is the whole ODI series and the five-match T20I series gone.

This was meant to be the comeback. Bethell has not played since England's ODI series against India in mid-July, and he had already sat out Saturday's warm-up win over Western Australia. Our own preview had him as doubtful for Friday. Doubtful has now become done.

That quote is the part that should bother England. Bethell has said he played through pain during the India series, and the soreness started in the T20Is before it. He did not just get hurt. He kept going on it.

The "three or four weeks" turned into a diagnosis of a chondral defect, which is cartilage damage, then surgery, then nearly five months on the sidelines. The list of what he has missed is long: the home Tests against Pakistan, the ODIs against Sri Lanka, the tri-series in Pakistan, and now all of Australia.

His Instagram line was short: "Gutted to be missing more cricket. [I will] be back stronger." Fair enough. But cartilage in a knee is not a hamstring. "Back stronger" depends on what the specialist says next week, not on how hard he works.

In the cruellest way, cricket keeps moving. Bethell opened for the first time in that India series and looked the part. Then Tom Banton took the job and made 394 runs at 56.28, with one hundred and four fifties, since his promotion.

Now Banton gets a full ODI series in Australia as Ben Duckett's partner with no one breathing down his neck. Five more good innings and that spot stops being Bethell's to come back to. That is not a knock on Bethell. That is just what 56.28 does.

There is a leadership hole too. Bethell was Harry Brook's vice-captain and was meant to share the job with Will Jacks on this tour. Jacks is also set to captain the fifth T20I, with Brook and Jordan Cox leaving early to get ready for South Africa. Jacks now carries more of it alone.

Root, who plays his 200th ODI on Friday, said the kind thing. Note the words "hopefully it's not too serious". Nobody at England is saying it isn't.

The first Test against South Africa at the Wanderers is on December 17, five weeks away. Bethell was named in the 15-man squad for that three-match series only this week. National selector Marcus North even hinted Bethell could be an option to open in Tests for the first time.

He is fighting Emilio Gay, Jordan Cox and Dan Lawrence for three places in the top six, and North says nothing is decided. A player who has not batted in a match since July, with a knee that broke down in a training session, is not the favourite in that race. England sending him home early, with "a busy winter ahead", tells you they are protecting the Test tour, not just this one.

England have called up Sussex allrounder James Coles early. Like Bethell he bowls left-arm orthodox, and he was already due for the T20Is, so he leaves the England Lions tour of St Kitts and lands in Perth on Thursday.

Hampshire quick Eddie Jack comes with him into the ODI squad, replacing Josh Tongue, who flew home with an injured big toe. Jack earned it: 5 for 42 in the Lions' 266-run thrashing of West Indies A this week. Both will stay on for the T20I series.

CricIntel's take: England's batting depth means they will barely miss Bethell in Perth. The worry is that a young batter being built as a three-format player has now lost most of a year to one knee. Get the Test call right, and do not rush him back for Johannesburg just because there is a gap in the top six.