Hooper joined from Celtic for £5 million last month but there are now doubts as to whether or not he will start the season.
He left Carrow Road on a stretcher with manager Chris Hughton hoping there was nothing to worry about.
"Gary has been taken for a precautionary X-ray. He got a whack on the shin, it was an awkward challenge," he told his club's Twitter feed.
"We'll wait and see what the X-ray shows but hopefully it's just a whack which will be a bit sore rather than anything more serious."
Bradley Johnson scored both of Norwich's goals as the Canaries claimed a 2-0 victory.
Ravel Morrison scored after 16 seconds as West Ham saw off Pacos de Ferreira 2-1 - the other goal coming from Modibo Maiga, while Crystal Palace lost 1-0 to Lazio.
Stoke drew 0-0 with Genoa, while Jason Puncheon's late winner helped Southampton beat Real Sociedad by the odd goal in seven.
Christian Benteke scored twice - once from the spot - and Ron Vlaar got one as Aston Villa beat Malaga 3-2 while Fulham went down 2-1 to Parma, Steve Sidwell registering.
Elsewhere, Hull looked good as they beat Real Betis 3-0 in Andy Dawson's testimonial.
Danny Graham, Sone Aluko and George Boyd got the goals.