Gallas also praised manager Arsene Wenger for delivering on his promise of giving youth a chance, following the departure of Thierry Henry this summer.
The defender was an outspoken critic of WengerÂ’s decision not to sign big name players during the summer, but now seems convince Arsenal have the talent already.
But the France international has warned against complacency and admits that SundayÂ’s trip to Anfield will sort the men out from the boys.
"Arsene Wenger was right. After the departure of Titi, he has trusted the group, the young players," Gallas told L'Equipe.
"What has changed this year is drive, collective desire, and fighting spirit.
"What I see is a group that is fantastic, our start to the season is amazing and we have great fun playing in such a team.
"But at the same time, all that is a little frightening. On Sunday at Anfield, we will know much more.
"I have said I will wait for the end of the season to talk about our run of results. We are just in October, and a lot of things can still happen.
"As a captain it is also my role to temper enthusiasm."
Arsenal produced a superb performance to beat lowly Slavia Prague 7-0 on Tuesday, equalling the biggest win in UEFA Champions League history.
Gallas added: "The match against Slavia Prague was an exceptional night. We achieved the same feat as Juventus.
"Now it would be nice to imitate them and win the Champions League."