London Broncos head coach Rob Powell says their second-half showing against Huddersfield Giants was unacceptable.
Powell's side remain second-bottom in the Super League table following their 46-10 defeat on Sunday.
He told BBC London 94.9: "At 16-10 we were well placed and looked like the more proactive team.
"We missed some opportunities and the nature of that capitulation, to concede 30 points in 20 minutes, is just not good enough at this level."
He added: "We try and prepare the players as well as we can but they dropped off there at the end.
"We put a lot of time and effort into building them up for this game. We were viewing it as a big game after the win against Widnes.
"For 60 minutes we were going alright.
"Our plays and our shapes were better than they have been for the last few weeks. We were better with the ball and defended pretty well in the first hour.
"It was coming together a little bit and that's why it makes it so disappointing that the scoreline ends up being what it does."