The Swede, appointed in the wake of Unai Emery's sacking on Friday, started life as Arsenal boss with a 2-2 draw at Carrow Road.
Arsenal came from behind twice, with Pierre-Emerick Aubameyang scoring both of the visitors' goals.
But Willock has hailed Ljungberg and insists the Gunners squad is fully behind the club's former winger.
The 20-year-old academy graduate told Sky Sports: "To be honest, we know collectively that we need to improve, whoever the manager".
It gives Ljungberg plenty to think about ahead of a home game against the Seagulls on Thursday night before an away trip to West Ham next week. "But we need to work on the transitions, we dominated and they break us too easily".
"I want this club to do well, it is only winning that counts. I wanted to win the game so I am disappointed but I have also seen some positive things".
The hosts took the lead against the run of the play after 21 minutes as Pukki's deflected shot off Mustafi found its way into the net.
Krul saved Aubameyang's penalty but it was retaken after VAR had adjudged four Norwich players had encroached into the box.
Arsenal began brightly but the defensive frailties which have characterized their recent form showed themselves again as Norwich's Finnish striker Teemu Pukki scored his first goal since September. "But from what I heard it was quite obvious, that's what the results are for".
"I saved the first penalty so it was frustrating that it had to be re-taken".
"I just said to Mesut Ozil as they were celebrating that they were lucky because the referee helped them a lot there".