The Juve striker made it 11 goals in his last nine Serie A games with a match-winning double on Sunday.
A goal in either half from Higuain moved his side seven points clear of Roma at the top of the table in a match that saw Nicolo Barella sent off for the hosts midway through the second half.
"I am in good shape and so is the rest of the team," Higuain said to Sky Italia.
"Cagliari are a good team and it was a tough game. The important thing was to win. We didn't start the first half the way we wanted to and it was really difficult, but we emerged in the end.
"We knew Cagliari had a strong home record and we would have to work hard to win. Fortunately, we got the goal, then we scored again. The red card helped and we came through it."
Massimiliano Allegri's men have won five league matches in a row heading into Friday's home match against struggling Palermo.
"Now we must rest and get ready for Palermo," said Higuain.
"We have only done our job, so we have to stay calm and make sure we continue like this.