A HAMSTRING strain for Essendon swingman Cale Hooker will see him on a modified program for what the club expects will be up to three weeks.

The 30-year-old was hurt at training over the past week.

Hooker made the All Australian side in 2014 as a defender but has spent more time forward in recent years, booting 41 goals in 2017.

It follows news of star midfielder Zach Merrett suffering a left ankle concern that will see him in a moonboot for a fortnight after going down on Friday.

The Bombers don't believe he is in danger of missing their round one clash with Greater Western Sydney on Sunday, March 24.

"While not acute, Cale presented with symptoms post-training and after consultation with our medical team a decision was made to place him on a modified program for the next two-to-three weeks," Richardson said.

"It is only a minor strain, and given he has had a solid pre-season to date, we are confident it will not have a major impact on his preparation."

Meanwhile, there is no guarantee Joe Daniher will be available for round one as he continues to recover from osteitis pubis, although he put in his biggest session of the pre-season last Wednesday.