The Argentine, who has been out injured since midway through last season, scored twice on his return to the first team
The Argentine, 34, has been out of action since midway through last season and delighted the travelling Nerazzurri supporters by coming off the bench to score twice.
"This double means a lot to me," he told the club's official website. "I'm delighted with my return and of course to score two goals as well.
"We played superbly today and we've got a fantastic group of lads here. There are loads of people I'd like to thank: my family, my kids, my team-mates, Andrea Scanavino, who worked closely with me in this period, Franco Combi and other doctors, other people I wouldn't like to forget.
"We really have got an exceptional group here and we're going about things the right way. Coming back into a team that's playing so well makes everything that much easier.
"We must keep taking each game as it comes - that's what we're trying to do. We've got a new group of players and a new coach so there's lots of work to do but we're on the right track."
Walter Mazzarri's side jumped to the top of the table with the win, though wins by Napoli, Roma, Juventus or Fiorentina this weekend could see them knocked off top spot.