Warrington starlet Matty Ashton suffered a hamstring strain in the win over Toronto, coach Steve Price confirmed.
Ashton, 21, pulled up midway through the second half after making a break, and was forced from the field.
Speaking in his post-match press conference, Price confirmed that it looked like a bad one, and it could see the former Swinton full-back on the sidelines for several weeks.
He sat out the defeat at Wakefield last week, but returned to the starting line-up for the 32-22 victory over the Wolfpack, with Stefan Ratchford switching to centre.
Warrington surrendered a 16-0 lead and were tied at 22-22 after the hour mark, before two Ratchford penalties nudged them in front.
Price said: “I thought we were in total control for the 15 (minutes) and last 15.
“Either side of half-time is a bit worrying but credit to the boys, sometimes you have to find the way in the early parts of the season to get that W, and we won in different styles to what we have in the past so that’s pleasing.
“To find a way and scrapping towards the back-end of the game I was very pleased with the lads.
“Overall, we are still learning, still developing as a group and that is the most positive sign.”