At about the 9:00 mark of the 1st quarter BYU had first and goal at about the 3 yard line. The play was a run up the middle for a little gain. There was a big pile in the middle of the field and Pay was at the edge of the pile. He came out of that play limping on his left foot it looked like. Then the next play was the short touchdown pass to Roberts, and it looks like Pay was limping after that play as well

He also didn't come out for the next series, so that looks like when the injury happened.
Did he get rolled up on his ankle on that play?