Fritz and his team-mates stunned Chelsea in Bremen on Sunday with Eljero Elia and Ludovic Obraniak scoring in the first half, before Felix Kroos added a third goal in the 89th minute.
The 2013-14 Bundesliga campaign was a tough one for Werder as they finished 12th, but they produced some strong results in the last few months of the season.
Werder drew with third-placed Schalke and defeated Hoffenheim, Hannover and Hertha Berlin, who all finished above Robin Dutt's side.
Fritz reckons Werder have built on that form in the close-season and started to show against Chelsea that they are a better side than last term's results suggest.
"We did a lot of things well in the second half of last season and now we are continuing that," the right-back said.
"We really worked hard in the preparations but we still have work ahead of us. You can see that we are a step further, but what's important are the matches in the [DFB-Pokal] and Bundesliga."
"We need to take our confidence from good actions and not from results," he said.
"The most important thing is that we implement things from training. I saw that over stretches today.
"We need to get more physical to create more consistent chances and not allow as much defensively."
