The Dempsey-less Cottagers began their campaign with an easy win over the Canaries, who will need to improve quickly after a crushing defeat under their new manager
Damien Duff and Petric had the hosts 2-0 up at half-time, before Petric, Alexander Kacaniklic and substitute Steve Sidwell completed the rout in the second half.
Martin Jol's side began the season without the wantaway American international Clint Dempsey amongst their number, but there were debuts for Croatian striker Petric - partnering Bryan Ruiz - and new right-back Sascha Riether.
Chris Hughton's Premier League debut as Norwich manager saw him hand debuts to new recruits Robert Snodgrass and defender Michael Turner, whilst left-back Marc Tierney returned for his first league match in nine months after injury.
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A simple pass back to the keeper was poorly cleared, straight to the feet of Bryan Ruiz, but the Costa Rican forward, an £11m signing from Twente for the Cottagers last season, could only lob harmlessly over the crossbar.
Five minutes later and the story of the match again involved Ruddy, but this time it was him showing his best, with a smart save down to his right to deny John Arne Riise's angled drive, before some 90 seconds later he was forced into a smart save from Petric.
With Fulham starting to dictate the play a goal seemed like only a matter of time, and in the 26th minute the home side obliged to open the deadlock, but Hughton will have been furious with his side's defending.
The Fulham backline were allowed to keep possession, and when left-back Riise wasn't pressured on the halfway line, the Norwegian hit a superb cross-field pass over his opposite number Tierney, sending Duff clear, who having broke the offside trip, flicked the ball past Ruddy for the first goal.
Fulham were comfortably in charge of proceedings and doubled their lead in the 40th minute, with a debut goal from former Hamburg striker Petric.
Initially, his sublime through pass put through Ruiz, only for him to be denied by an excellent challenge from Ryan Bennett, but from the resulting corner Petric headed past Ruddy - despite the best efforts of a man on the line - to double the home side's advantage.
Unquestionably dissatisfied with his side's opening 45 minutes to the season, Hughton sent on striker Steve Morison for Andrew Surman at half-time, and switched his formation to 4-4-2 in an attempt to disrupt Fulham's rhythm.
Nevertheless, the first chance of the second period went to the home side, with Riise rampaging down the left-side again, but his cutback for Kacaniklic was cut out by Turner.
In the 54th minute however, and the game was over as a contest, thanks to a second goal for Petric.
Another neat passing move involving Diarra, Dembele and Ruiz, allowed Petric to find space 30 yards from goal, and when the ball arrived at the Croatian's feet, he rifled a left-footed shot goalwards, which deflected off Turner, and nestled in the back of the net.
Twelve minutes later, and Petric turned from scorer to provider as Fulham cut the Norwich defence apart once more to make it 4-0.
The imperious Dembele again found space and attacked the Norwich defence before feeding Petric, whose terrific backheel freed Kacaniklic, who converted coolly.
With the damage done, Martin Jol replaced the outstanding Petric, and introduced another new signing, the former Wigan striker Hugo Rodallega.
The Cottagers, in front of former manager Roy Hodgson, looked extremely impressive, with terrific movement off the ball ensuring that the man in possession always had several options, and the away side simply had no answer.
Steve Sidwell replaced Bryan Ruiz with 10 minutes remaining and the former Aston Villa midfielder got his name on the scoresheet in the 86th minute from the penalty spot.
Another wonderful pass from Dembele found Rodallega, who was cleaned out by Turner, who had endured a torrid debut, and Sidwell smashed the spot-kick past Ruddy, into the roof of the net to seal the rout.