The 23-year-old midfielder netted twice to help Alan Pardew's side come from behind to beat European champions Chelsea at St James' Park on Saturday afternoon
The Frenchman started his first game at St James' Park on Saturday afternoon, and led the Magpies to a 3-2 victory over Rafa Benitez's men.
He told the Newcastle Chronicle: "It is up there with my best moments of my career. I’m not sure if it is quite the best yet.
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"Even in my wildest dreams I couldn’t have imagined that! I’m happy to come away with the victory. We now have the confidence to go on and win more games."
The 23-year-old is now targeting an improved Premier League position, with the Tyneside outfit still languishing in 15th following a poor start to the season.
"Since I arrived I said we could really move up the league table," he continued. "I signed and knew full well the position Newcastle were in. But I wasn’t too worried; I knew there had been some injuries.
"We can finish in a much better position. Now we’ve had two victories since I’ve been here and that’s fantastic. But we must not get too complacent. It isn’t going to be easy; it will probably be even harder. It’s something we’re ready for and we’ll keep battling."
Sissoko was understandably popular with the St James' Park faithful following his debut double and has paid tribute to the club's fans.
"Their support was brilliant," he added. "The fact that we won was also thanks to their support.
"I couldn’t play the full 90 minutes last time. But the public supported me all the way through against Chelsea."