England seamer Toby Roland-Jones is set to miss this winter's Ashes after scans confirmed he has a stress fracture in his back.

Roland-Jones had made himself a certain selection if fit in a squad which will be named next week, after taking 17 wickets at an average of under 20 in four matches in his maiden Test summer at the age of 29.

But after initially complaining of pain in his side, he had to leave the field mid-over for Middlesex in this week's penultimate round of Specsavers County Championship Division One fixtures against Lancashire at Lord's.

His county issued a brief statement on Friday afternoon, confirming an injury which has a typical recovery time of between six and 12 weeks.

It read: "Middlesex Cricket are extremely disappointed to announce that the result of the medical scan which Toby undertook yesterday has revealed that he has a stress fracture in his L5 vertebra (lower back), which will mean that he will take no further part in the domestic season."

England's high-profile winter begins when they leave for Australia on October 28.

It is understood the injury leaves Roland-Jones out of contention to be named in the squad next Wednesday, with the first Ashes Test only two months away - almost to the day, in Brisbane on November 23.

England's selectors must therefore cast their net wider to work out who will be their back-up seamers at the Gabba and beyond.

Toby Roland-Jones looks on after taking Jermaine Blackwood's wicket for England (Getty)

They are keen to take Mark Wood on tour, with his extra pace such an asset, as long as he can continue to demonstrate his recovery from the heel problem which interrupted his summer.

Roland-Jones' absence, however, may mean a return for his Middlesex team-mate Steven Finn - while other pace options include Jake Ball and uncapped Somerset bowler Craig Overton.

A potentially depleted bowling stock is not the only issue, with two batting positions far from settled either.

Tom Westley and Dawid Malan are incumbents at numbers three and five, but have not sealed their places by any means.

Former Test opener Alex Hales is a left-field choice among a clutch of other contenders, including his England limited-overs team-mate Jos Buttler.

Their white-ball captain Eoin Morgan has endorsed Hales' credentials, however, noting he has proved his resilience as well as his ability of late.

Morgan describes Hales as a "massive part of our side", opening the innings, as England try to consolidate their 1-0 Royal London Series lead over West Indies - starting in Bristol on Sunday in the third match of five.

Against the red ball this summer, Hales has had mixed success - with one double-hundred accounting for more than half his output in Specsavers Division Two for Nottinghamshire - as he has tried to reinvent himself in the middle order since losing his Test place last year.

"When you get dropped from any team there are a lot of questions you ask yourself, and there's a lot of questions asked of you by a lot of people outside our bubble," said Morgan.

"So coming back from that shows huge character, and to show the form he has has been incredible."