Cornwall head coach Neil Kelly says his side got a "reality check" in their 36-24 loss to Hunslet.
Having won for the first time last week, Cornwall were 12-0 up midway through the first half after tries by Aaron Jones-Bishop and Tom Ashton but conceded three scores before the break.
A Liam Whitton try made it 18-all early in the second period before three more Hunslet tries secured the win.
Harry Aaronson's last-minute score provided some consolation for Cornwall.
"It's a bit of a reality check coming here and playing a team from the heartlands," Kelly told BBC Radio Cornwall, a week on from his side's historic first win at West Wales Raiders.
"We're on a learning curve and, for 20 minutes, we showed ourselves that we can do it.
"We saw the effect it had on the opposition, but 20 minutes doesn't win you the game, we've got to do that for longer periods - no team ever does it for the full 80, but certainly you need to do it for a lot longer."
The loss sees Cornwall remain second from bottom of League One with one victory from 12 games.
The club were only formed late last year and are in their first season as a professional outfit, and Kelly says he is starting to see a mindset change from his players:
"We've used today to move from where the motivation for us playing was fear. Up to now we've been playing teams and thinking 'as long as we can keep the scoreline down then we'll be happy with that'.
"This is the first game where we've really played and we've gone out to compete with them, and for long periods we've competed with them.
"But fair dos to them they've got the win. Everybody that was here can see we did have them on the rack, but we didn't do the right thing at that point."