Fox's side travel to Manchester Storm on the back of their best spell of the 2019-20 season.
Steelers top Group C with eight points from six games. They are also joint top of the Elite League.
Asked about the significance of Friday's match - given the early rounds of the tournament don't always capture the fans' imagination - Fox said: "If you want to win the Challenge Cup, it is important you are able to put yourself at the top of the table and I think if we win our group and win out these last two games and finish in second place it would allow us to pick our opponent after Dundee (Group A) picks an opponent.
"And you play the lowest seeded opponent from there, so I think it is important for us to do a job, on Friday.
"You don't want to lose momentum. Losing is contagious" said Fox.
"There is no reason to put that element in our game when things are going the right way.
"We will take it serious and be ready to go."
The coach had warm words for the latest recruits to the Steelers' roster.
Marek Troncinsky had excelled on the power play, something he'd been good at his whole career, said Fox.
Mikko Kuukka had done a similarly effective job on the power play.
The new skaters (including Lucas Sandstrom) had been welcomed in by the group of "high character" players in the dressing room.
"All of them have fitted in without any issues."
But have the three imports markedly improved the team that had started out the season?
"That is a tough question to answer, at this stage" said the team boss.
"They have been here for a short period of time...once Jonas (Liwing) and Aaron (Johnson) come back then we will figure things out from there. But right now I am living in the present."
Steelers beat Fife Flyers 4-1 at the Arena on Wednesday night, and could have had more goals, having outshout the Scots 38-16.
Two of their goals were power play, one of them shorthanded.
Ben O'Connor's late insurance goal was his first of the season.