The 34-year-old received an initial diagnosis during the game, but the full report won't be available until he undergoes further tests on Saturday morning.
"Well it doesn't look good, but there's nothing definite yet," Gibbons said late Friday night. "They'll re-examine it tomorrow but it doesn't look good."
Perez became one of the surprise stories of the Blue Jays this season when he exceeded expectations by securing a permanent spot on the 25-man roster. He responded to the opportunity by breaking a 35-year-old record with 22 1/3 consecutive innings without allowing an earned run to begin a Blue Jays career.
The Dominican Republic native didn't allow an earned run until the streak finally ended against the Dodgers on July 24. That surpassed the previous mark of 21 1/3 scoreless innings set by Victor Cruz from June 24-31, 1978.
Perez often was forced to throw a lot of innings as part of an extremely overworked Blue Jays bullpen. All but seven of his 19 appearances were more than one inning, and he threw 56 pitches in just 1 2/3 innings on Friday before suffering the injury.
Gregor Chisholm is a reporter for MLB.com. Read his blog, North of the Border, and follow him on Twitter @gregorMLB. This story was not subject to the approval of Major League Baseball or its clubs.