The 35-year-old, whose contract runs until June 2010, has not ruled out signing another deal, although matching Brazilian Romario's reputed 1,000-plus career goals looks impossible.
"I'll try to carry on as long as I'm playing like this. Knowing myself, it will be a difficult day when I stop," Inzaghi told Sky television after two trademark goalpoaching strikes.
"I try to work like I always have. I know the things that keep me fit. I must say the coach (Carlo Ancelotti) is great because he lets me have a breather when I need it as at nearly 36 I can't train all the time."
"I prepared it yesterday because I hadn't realised that my first professional goal was against Siena so it was destiny that my 300th would again be against Siena," he smiled.
"My team have given me a great hand. Strikers live for things like this but results like when Milan won the Champions League that evening in Athens offer much more satisfaction," added Inzaghi, who scored a hat-trick in a 3-0 win over Atalanta last weekend.
He picked out Milan's 19-year-old striker Alberto Paloschi, on loan at Serie B side Parma, as a potential successor.
"I see my desire in him. I hope one day I can give him my number nine shirt."
