The Ayrshire side defied the odds to knock out favourites Inverness and book their place in the quarter-finals of the cup competition with an impressive 2-0 win last week.
Sissoko sees no reason why Killie cannot build on the result and force their way into the top half of the table this term.
Kilmarnock head into their weekend match against Motherwell just three points behind sixth-placed Aberdeen and Sissoko says the dressing room is full of confidence.
The defender said: "It's very important to be in the top half of the table because the top six is always more exciting. So I hope we can finish in the top six this year.
"Everyone is focused and I think we can be in the top six.
"We had a good game against Inverness last week and the confidence is high now.
"Hopefully we can win this game. Motherwell are a good team, with good strikers, but hopefully it will be a good game for us."
Boss Kenny Shiels believes Killie can once again take advantage of their underdogs tag to come out on top when Motherwell come calling.
He said: "We're looking positive and we want to stay positive for as long as we can.
"We went into the game as underdogs last week and we did well.
"We are doing the same again this week and everybody is up for this game.
"It's great to get a result like the cup game. It gives everybody a lift and you can't wait for the next game."
However, he is under no illusions about the challenge facing his players, adding: "I expect a tough game.
"They are a really good football team and they have done brilliantly.
"We've played the league leaders, we've played the second-placed team and now we play the joint second team in a matter of nine days.
"The top three in the league - it's a big test for us."