Fleetwood Town manager Graham Alexander does not expect League One to be an easy prospect, despite winning on their debut at third-tier level on Saturday.
Goals from David Ball and summer signing Jamie Proctor gave the Cod Army a 2-1 victory over Crewe at Highbury.
Alexander told BBC Radio Lancashire: "There are a few players who think they should be at this level anyway.
"They have to go out and prove that and I thought they did that on Saturday, but one game doesn't make a season."
The former Scotland international continued: "We have to make sure we work just as hard, week in and week out."
Fleetwood have made rapid progress up the English football pyramid over the past decade - promotion to League One in May was their sixth in the space of 10 seasons.
They face Rotherham in the first round of the League Cup on Tuesday.