Inter midfielder Hernanes wanted to show Lazio president Claudio Lotito he was wrong to sell him, firing his new team to a 2-1 win on Sunday.
Hernanes struck twice after Antonio Candreva had put hosts Lazio ahead, seeing Inter to their win at Stadio Olimpico.
The Brazilian joined Inter from Lazio in January 2014, with Lotito saying he had no other choice because Hernanes may have left on a free transfer.
Hernanes said he was inspired to prove Lotito wrong.
"I feel bad for the fans but I wanted to show Lotito he was wrong after he said he did a great deal when he sold me," he told Sky Italia.
"I feel physically much better now and I realise I can make the difference playing behind the strikers. These two factors make me feel more comfortable than ever."
Hernanes felt he had finally shown his new club what he is capable of.
"It was a special match and I wanted to put in a great performance," Hernanes said.
"I wanted to show the Inter supporters that I'm better now and that the real Hernanes wasn't just the one we saw in a Lazio shirt."
