The Bianconeri have been beaten by Udinese and Roma in the opening weeks of the campaign, having strolled to a fourth straight league title last season.
However, the summer departures of Arturo Vidal, Carlos Tevez and Andrea Pirlo appear to have hit Juve hard, though Hernanes - an €11 million signing from Inter - says they must improve and fast.
"If we're talking about the level we play at, then it might take some time to know each other and do things naturally," he told Sky Sport Italia.
"In terms of results there are no excuses and we have to start picking up three points. Juve are still the team to beat, we have maintained a strong base and are the strongest team in Italy.
"But we are ready, we have trained well together these last few days. We are in good condition and we're ready."
Juve also won the Coppa Italia last season, but were losing finalists in the Champions League.
However, Hernanes is confident Juve can challenge again in Europe's premier club competition, adding: "At Juve you have to try and win everything so we're definitely one of the favourites."