When Bob Willis was captain of England, back in the early 1980s, he reckoned it would take three men to replace Ian Botham. That might be a bit excessive in the case of Andrew Flintoff, but the selectors will need to give themselves a couple of options in case the Lion of Lord's pulls up lame before the third Test next week at Edgbaston.
Wonderfully well though England played during the 2005 Ashes series, they were helped by having a clean bill of health until the final match, at The Oval, when Simon Jones failed to recover from an ankle injury.
It is already a different story this time with Kevin Pietersen – the team's best batsman on paper, if not on the field at either Cardiff or Lord's – out of the picture following an Achilles operation.
Choosing Ian Bell to replace Pietersen should be straightforward. But national selector Geoff Miller, and his colleagues James Whitaker, Ashley Giles and Andy Flower, will want to make sure England have batting and bowling cover for Flintoff when they announce a squad of 13 or 14 tomorrow morning. And that is the tough bit.
Much has been made of trying to achieve strength in depth, and it is true to say England are reasonably well served on the pace-bowling front with Steve Harmison and Ryan Sidebottom ready to play next week, if required.
But if Flintoff's optimism about that sore knee proves to be wide of the mark, and England decide that conditions demand he be replaced with a batsman, it is pretty much anyone's guess where the finger will point.
Kent boys Rob Key and Joe Denly have their admirers, Worcestershire's Stephen Moore made a century against Australia for the England Lions and Warwickshire's Jonathan Trott has three big championship hundreds this season and knows Edgbaston better than most.
Any one of those would be a stab in the dark – even Key, who has not played a Test for more than four years.
So who, then? Well, England jettisoned Owais Shah with almost indecent haste after deciding, on the strength of three Tests in the Caribbean, that he could not cut it at No 3. But he may be their best answer if a No 5, 6 or 7 is needed next week.
The biggest unknown, five days out from the Test, is the pitch with the Edgbaston groundsman Steve Rouse having said it resembled "jelly" because of all the recent rain.
Groundsmen, though, generally look on the gloomy side – unlike England's medical experts, who have tended to err on the side of optimism. Putting Pietersen's recovery time at around six weeks could be a case in point, although the selectors have decided to name him in their provisional squad of 30 for September's Champions Trophy tournament in South Africa. Hamphire's Michael Lumb and Denly are the two newcomers in the party.
Possible Test squad: Strauss (capt), Cook, Bopara, Bell, Collingwood, Prior (Wkt), Flintoff, Broad, Swann, Anderson, Onions, Shah, Harmison, Panesar.