Ronaldinho finally completed his long-awaited switch to the Serie A giants on Thursday, training with the team for the first time the following day.
"We will try to win the Scudetto and now that Ronaldinho has arrived we can win everything," Pato told Italian sports daily Gazzetta dello Sport.
"We will fight for the UEFA Cup and for the Copa Italia, even though the league is our first priority."
Ronaldinho's arrival has generated a wave of excitement which the Italian media are dubbing "Dinho mania".
Thousands of spectators gathered outside Milan's training ground in the hope of catching a glimpse of the new signing on Wednesday, while 40,000 fans turned up to the San Siro 24 hours later for his presentation ceremony.
Such fan fervour does not surprise Pato, who is used to the affection afforded to his fellow Brazilian in his home country.
"Dinho deserves this welcome because he is one of the great ones, a phenomenon," added the 18-year-old.
"I grew up in Porto Alegre and Ronaldinho was born there, In the city all they talk about is that he is a legend. I dream about arriving at his level. He has brought to Milan much happiness, he plays while smiling and that is his secret."