The Italy international missed the opening stages of the season through injury and struggled in his first few games for the Old Lady, yet feels he is close to his best after converting a trademark free kick in the Bianconeri’s 2-0 League win over Empoli on Saturday night.
"Personally, I'm growing," the 35-year-old said. "I'm working hard and well during the week. I'm now close to my best condition."
Following Roma’s 2-0 defeat to Napoli earlier in the day, Juventus have now built a three-point lead at the top of the Serie A standings as they bounced back after their shock midweek loss to Genoa.
"It was important to win," Pirlo said. "We needed to immediately put the loss at Genoa behind us and take advantage of Roma's defeat.
"It's an important sign for us, a clear message to all of the Scudetto challengers.
"But my mind is already on Tuesday evening. The Olympiakos game is effectively a final."
Juventus have not been at their best in Europe, languishing in third place in their group after successive losses to Atletico Madrid and Olympiakos.
And Pirlo is targeting only one result ahead of the reverse fixture against the Greeks this week.
"We must play at our best, with zero mistakes,” he said. “We only have one result available to us: victory."