Luke Norris will visit a specialist to ascertain the severity of the injury he picked up on Saturday.
The U's striker went down just before half-time in the game against his former club Swindon Town, and was stretchered off before being taken to hospital.
U's Physio Tony Flynn has been monitoring the situation over the weekend, and updated the official website first thing on Monday morning.
He explained: "It looked an innocuous incident but Luke was in a lot of pain, and had to be stretchered off the pitch.
"He went to hospital on Saturday, had an X-Ray, and that revealed that there were no fractures around his ankle joint.
"The next stage is to see the specialist today, and he will make a decision about how soon the MRI scan can take place.
"In some cases, it can be done straight away, but sometimes it is delayed to let the swelling subside.
"The scan should tell us exactly what ligament and /or soft tissue damage there is.
"There is no knowing what the timescale will be for Luke's recovery until the scan is assessed, but the early indications are that it isn't his Achilles Tendon."