Lancashire coach Glenn Chapple suspects James Anderson will only suffer for a “few days” after he was injured during their loss to Hampshire in the One-Day Cup.
Anderson, who has taken 575 Test wickets for England, took a ball to the inside of the knee from James Fuller’s drive.
“It is a nasty blow in a painful area. We don’t know but we think that it will be a nasty bruise that will settle down in the next few days,” Chapple said.
“The physio will see him in the morning and he walked off there.
“It is a difficult are. As soon as there is any swelling in there it will restrict your movement and limit your strength. I imagine it will be painful for a few days.”
A total of 55 players have been invited to work under ECB guidance in the coming weeks.
The swing bowler completed the landmark at Headingley.
But the ICC has rejected claims the tournament will be postponed, insisting a number of contingency plans are being considered.
He will not return from his family home in Tasmania even if the delayed season gets under way later this summer.
No domestic cricket can take place until at least August.
An expanded training group of up to 45 is due to be named on Friday.
The governing body still aims to stage a shortened domestic season.
Professional cricket is on hold until at least July 1.