Petkovic can see Lazio pushing their way towards Europe after conquering San Siro.
"We are playing very well, although Inter deserved something more tonight," he said of the 3-1 victory.
"We had chances even after going 3-1 up, but we weren't clinical enough. I compliment my players for the result and for extending our positive streak.
"Now there are three teams fighting for the Europa League. If we win the last two, I am sure we can make it."