The Brazilian is hoping that the Nerazzurri can now embark upon a winning streak and has vowed to fight for his first-team spot following Danilo D'Ambrosio's arrival
The Nerazzurri finally triumphed for the first time in 2014 thanks to Walter Samuel's second-half goal at San Siro.
Jonathan believes Walter Mazzarri's men can go on a winning run now that they have finally broken their duck.
"All that mattered was winning, especially at a time like this, where we had some issues finding the target," the Brazilian told the club's official website.
"Winning breeds confidence for the rest of our league campaign."
Inter added midfielder Hernanes and full-back Danilo D'Ambrosio to their ranks during the January transfer window and Jonathan is delighted with both arrivals - even if the latter's signing means more competition for him in terms of regular first-team football.
"Hernanes is a quality player, he's classy on the ball, as you saw [against Sassuolo]," he said of his compatriot. "And we mustn't forget that was his debut.
"D'Ambrosio joining changes nothing for me. I'll keep working. I'm always very calm when I play; I'm always up for it.
"It's great for the team that we have another option. Even if the best full-back in the world came in, I'd still keep working. I respect the coach's decisions."