Sean Clare's confidence was boosted after the side's performance in the win over Motherwell last week, but he insisted they can be even better as they head to Glasgow this weekend.
The Jambos booked their place in the Betfred Cup quarter-finals after their 2-1 victory last Friday, but they are back in league action when they face Celtic on Sunday.
"It was a really good win for us and it should give us confidence moving onwards," Sean told the media.
"It wasn't a good performance against Ross County but we put it to bed after the last game. We can't keep thinking about it now, we've just got to move on and try and be positive every game and get better and better.
"We're not sitting on the Motherwell win thinking 'yeah we're done', we need to be even better on Sunday."
Celtic have won 2-1 in each of the last three games against Hearts but Sean is condifent he and his teammates can overturn that scoreline.
"If you go out there with the right game plan and execute it, you've always got a chance.
"We've got a really good squad, we've made a lot of good additions, there's a lot of competition for places and with the players we've got, we're more than capable of doing it.
"We have to go there and try and make it as difficult for them as possible, not let them play how they want to play. That'll help us. Maybe the fans will turn, maybe they won't, but it should help us in the game anyway."
To watch Sean's press conference in full on HeartsTV, click here.