Allen was ruled out for the game.
Allen suffered the injury with just over two minutes left in the second quarter. Allen's right knee appeared to buckle as he came out of a break and he fell to the ground. Teammates gave Allen a hug as he left the field. Allen was having a good day, with six catches for 63 yards.
Allen had 67 catches for 725 yards and four touchdown catches last season through eight games and was well on his way to his second 1,000-yard season, but he suffered a kidney laceration in the eighth game and missed the rest of the season.
In June, Allen signed a four-year contract extension worth more than $44 million.