Yorkshire bowler Ryan Sidebottom could be out for "several weeks", according to director of cricket Martyn Moxon.
The 37-year-old seamer injured his calf in the County champions' opening victory against Worcestershire.
"He is likely to be missing for several weeks," Moxon told the county's website.
"He is set to have a scan in the next day or so and once we have the results back we will have a better indication of how long he'll be missing."
Meanwhile, Moxon is confident that batsman Aaron Finch will be fit to join up with the county in May.
The Australian suffered a hamstring injury playing for Mumbai Indians against Rajasthan Royals on Tuesday and is set to miss the whole IPL campaign.
"We remain hopeful that Aaron will be with Yorkshire at some stage in May," Moxon added.
"It is disappointing news for him and a great shame that he'll miss most of the IPL season."