Norwich City's summer signing Gary Hooper was carried off on a stretcher as Bradley Johnson's brace secured a winning finale to their pre-season campaign on Saturday at Carrow Road.

Hooper twisted awkwardly early in the second period after trying to roll Pana defender Gordon Schildenfend. The former Celtic hitman was visibly in pain as he clutched the back of his left knee during treatment pitchside before being stretchered away.

Hooper had looked impressive in a front-running role during the opening period before dropping deeper with the half-time arrival of Ricky van Wolfswinkel, but City will now face an anxious wait to assess the extend of Hooper's injury over the coming days ahead of the Premier League kick-off next weekend.

Johnson's headed brace in each half proved too much for the Greeks, who struck John Ruddy's post from point blank range before half-time. Johnson rose unchallenged inside the visitors' six yard box to glance home Robert Snodgrass' dipping free kick inside the first four minutes after Hooper had been the recipient of a rather crude challenge from the imposing Schildenfend.

Ruddy spilled the Greeks' first set piece from Mehdi Abeid in a congested penalty area but Wes Hoolahan offered unlikely defensive ballast to clear City's lines. Abeid's crude flick on Hooper presented another inviting chance for the hosts, but this time Johnson was well-patrolled as he attempted to repeat his successful foray from another teasing Snodgrass delivery.

Anastosios Lagos's ambition almost proved his undoing when a meander out of defence saw him pick-pocketed by Johnson to trigger a swift Norwich counter. Russell Martin's overlapping run gathered Snodgrass' back flick, but Hooper was unable to guide the cross inside Stefanos Kapino's far post.

Ryan Bennett's strike then deflected wide after City had raided down the opposite flank, but Chris Hughton's side were fortunate to remain ahead in the 22nd minute when Thanisis Ntinas contrived to head against the post from barely four yards after Javier Garrido could only divert Schildenfend's initial header from another probing Abeid corner.

Hooper stumbled when primed to test Kapino following excellent interplay between Hoolahan and Maritn Olsson that carved the Greeks' open down the left. City appeared content to concede possession and territory as the half elapsed with Ruddy a virtual spectator. Pana's Emir Bajrami's miscued free kick on the edge of the City penalty area typified the lethargic flow to a contest that had started brightly. Abeid claimed set piece duties from the diminutive wide player shortly after, but Martin's sense of danger helped Norwich's new club captain clear at the far post. Hughton withdrew the full-back, Olsson and Snodgrass at the interval with City's Dutch summer signings and Steven Whittaker introduced. Leroy Fer was deployed in a wide left role with Hoolahan swapping to the opposite flank but Hooper tellingly dropped into a more withdrawn role in support of Ricky van Wolfswinkel.

Van Wolfswinkel's first contribution was to harass Girogos Koutroumpis into conceding a corner that Garrido disappointingly struck into the side netting. Hooper's attempts to shield the ball from Schildenfend ended in an awkward twisting movement that left City's new boy in a heap. Norwich's medical staff immediately signalled for a change before the stretcher bearers emerged from the tunnel area.

Elliott Bennett replaced Hooper which prompted another positional switch for Hoolahan but City doubled their lead through the prolific Johnson in the 59th minute when the midfielder anticipated Garrido's cross to powerfully head past Kapino from 12 yards out.

Pana's big summer signing, Markus Berg, failed to match the Norwich goalscorer with a glancing flick at the opposite end that slithered well wide of Ruddy's left-hand post. Fer and Hoolahan combined smoothly for Elliott Bennett to test Kapino with a dipping hit from 20 yards the Pana keeper tipped over then Ruddy mopped up at the other end when Abeid's lift freed Berg - but the Swede's heavy first touch was an open invitation for City's England international.

Pana's search for a lifeline predictably saw the Greeks revert to the set piece threat they had offered in the opening quarter but Michael Turner hooked clear after David Mendes Da Silva's initial header struck the back of the big centre-back. Van Wolfswinkel's classy pivot bought him the space he needed but the scuffed right-foot hit failed to match the initial artistry before a back-pedalling close range header dropped wide. Kapino then was forced to push away Redmond's strike in between the Dutch striker's burst with City looking to apply a final flourish.

• Norwich: Ruddy, Martin (Whittaker 45), Turner, R Bennett, Garrido, Johnson (Redmond 80), Tettey, Snodgrass (van Wolfswinkel 45), Hoolahan, Olsson (Fer 45), Hooper (E Bennett 57). Subs (not used): Bunn, Howson, Becchio, Butterfield, Ayala.

• Goal: Johnson (4, 59)

• Panathinaikos: Kapino, Koutroumpis (Triantafyllopoulos 63), Da Silva, Lagos, Bajrami (Mouzakitis 90), Marinakis (Spyropoulos 85), Kapelis (Berg 45), Abeid (Chouchoumis 74), Maroto, Schildenfend (Donis 78), Ntinas. Subs (not used): Tampakis, Berg, Anastasopoulos.

• Referee: C Pawson

• Attendance: 14,054