Greg Chapple confirmed that the 25-year-old had suffered a "reasonably bad" problem, making him a doubt for the start of their T20 Blast campaign
Lancashire's injury woes have deepened after allrounder Liam Livingstone was ruled out with a rib problem.
The 25-year-old joins James Anderson, Tom Bailey and Saqib Mahmood on the sidelines ahead of the T20 Blast which begins next week.
Lancashire face Sussex in the County Championship before beginning their T20 campaign against Leicestershire on Friday, July 20. He has been ruled out of the four-day clash and will be re-assessed next week.
"He's pulled an intercostal muscle reasonably badly," coach Glen Chapple told BBC Radio Lancashire. "We can't hide that it's a blow before the T20.
"He's a big player for us, as batsman, bowler and fielder, so it's a big blow. Hopefully he will still play a part in the T20."
Mahmood was set to feature for the England Lions before his injury
And while Lancashire could welcome Glenn Maxwell back into the side following Australia’s elimination from the World Cup at the hands of England, they will be without Mahmood, who would have been unavailable anyway without injury due to his England Lions selection.
"He felt tightness," said Chapple of the 22-year-old.
"He feels if from time to time, but this was little bit more than he normally does. There's a chance it could be a bit more. We'll see."
As a result, left-arm seamer Toby Lester, who had been on loan at Warwickshire, has been recalled from his stint at Edgbaston. With Anderson, Bailey and Mahmood all absent, the Red Rose county's seam-bowling stocks are being tested.
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