Ryan Sidebottom has been ruled out for approximately a month with a right calf strain.

The veteran Yorkshire swing bowler, 34, suffered the injury in training earlier this week, and will miss some crucial matches in both Twenty20 and County Championship cricket.

He is set to miss the rest of the t20 group stages and almost certainly a quarter-final tie should the White Rose qualify, while a worst case scenario would see him ruled out of four Championship matches too.

Sidebottom is out of trips to Hampshire and Derbyshire, while matches at Leicester and Northants come in the space of nine days from July 27.

It is a blow Yorkshire did not need as they are also set to be without overseas star Mitchell Starc beyond the end of the t20 group campaign on July 8.

“At the minute, it’s looking like Mitchell could be finishing with us at the end of t20,” said Martyn Moxon, Yorkshire’s director of professional cricket.

“He’s potentially got stuff the Australian selectors and their strength and conditioning people want him to do. Cricket Australia will call the shots.”