Jack Leach's hopes of a home Test debut at Lord's next week are over, after he sustained a broken left thumb during Somerset's warm-ups on the final morning of their Championship clash with Hampshire at Taunton.

Leach's injury was cruel timing for a bowler who fought his way into the Test XI against New Zealand in Christchurch in March, given that Ed Smith, the new national selector, is set to unveil the England squad for the first Test against Pakistan on Wednesday.

Leach, who had to overcome a major setback two winters ago, when his bowling action was adjudged to be illegal during a routine test at Loughborough, performed creditably on debut in New Zealand, claiming two wickets, but was unable to bowl England to a series-squaring victory on the final day of the tour.

"Jack Leach has sustained a broken left thumb," read a statement on Somerset's Twitter feed. "It's too early to know how long he will be out for at the moment."

In his absence, Moeen Ali is likely to earn a reprieve in England's Test squad, having made way for Leach's debut at the end of a torrid winter. However, he has endured a lean time this month, spending more time on the sidelines with Royal Challengers Bangalore in the IPL.

Moeen has claimed only one wicket in two outings in the tournament to date, and shown little sign of a return to form with the bat either, making scores of 1 and 10.

Other options for a spin berth could be Leach's 20-year-old Somerset team-mate, Dominic Bess, while Nottinghamshire's veteran Samit Patel can never be entirely ruled out, having made his most recent Test appearance against Pakistan in Sharjah in 2015.

The outside bet for a squad call-up would be Surrey's teenage spinner, Amar Virdi, who has been the toast of the county circuit this season after claiming 18 wickets in four first-class matches to date.

"For me it's very early days, and my focus is trying to cement my place for Surrey," Virdi told ESPNcricinfo. "If anything comes of that, then that's good."

Either way, it is the second time in three Tests this years that an England spinner has made his debut then suffered an injury before he could add to his solitary cap. The Hampshire legspinner Mason Crane is suffering from a stress fracture of the back, having debuted at Sydney during the fifth Ashes Test in January.