Hooper joined from Celtic for £5million 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.
In Finland, Arsenal struck a possibly big psychological blow to Manchester City as they beat them 3-1.
The Gunners belied the amounts spent by the respective sides over the summer as they blew City away, with Theo Walcott, Aaron Ramsey and Olivier Giroud putting them clear.
Alvaro Negredo replied for City.
Nicolas Anelka continued his fine pre-season form as he scored again for West Brom - joined on the scoresheet by Markus Rosenberg - in a 2-0 win over Bologna.
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.
Adam Lallana, Morgan Schneiderlin and Jos Hooiveld scored Saints' others.
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.
Later in the day, Fabricio Coloccini earned Newcastle a 1-1 draw with Braga.