it could well be a wait and see zone. Having seen someone tear a calf (Grade 3) on the pitch he definitely didn't do that. If he'd done that he wouldn't have got near scoring a run. So you're probably in the zone where it's going to be somewhere between 3-6 weeks and they'll only know more when they know more.
1 day - even with an MRI - is not a lot of time to figure out how long muscle is going to take to repair.