The French club arrive at Wheldon Road tomorrow having won just twice all season with chief Steve McNamara under increasing pressure.
Castleford, for their part, have lost just twice but Powell is taking nothing for granted.
“Last week the Dragons showed for a large period of the game against Wigan they’ve a team that can trouble the best defences in Super League,” he said of the French side who had led 21-0 before losing 32-23.
“They have a huge and very physical forward pack that we’ll need to deal with first and foremost and they started to play very quick with a number of offloads last week. They played a lot better for a big chunk of that game – then Wigan belted them for a period. But we know they’ll be a real challenge on Sunday.”
That will be especially true if Castleford continue their own worrying trend of badly switching off in the second half.
Struggling Huddersfield Giants scored four tries against them after half-time last Sunday when Tigers had been 28-6 ahead at the break.
“We are playing well for periods and having some really positive periods,” added Powell.
“We just want it to be a bit longer. We’ve got Catalans and then Wigan over our next block of games, plus Wakefield and Hull and the start of the second half will be important for us.
“We are playing really good teams in the next block and we want to be more consistent.”
He is forced into two changes, winger Greg Eden sidelined due to a recurring hamstring issue and prop Junior Moors with concussion, although James Clare and Matt Cook are fine replacements.
Catalans have problems with Greg Bird, Paul Aiton and Louis Anderson all dropping out, Lewis Tierney, Alrix Da Costa and Lucas Albert replacing that trio in the 19.
Meanwhile, Castleford winger Kieran Gill has begun a month’s loan with League 1 Oldham.
Gill, 22, suffered a serious injury while scoring on his Super League debut for Tigers last June.
He required a knee reconstruction but is starting back now.
Powell admitted: “Kieran’s had the toughest of injuries and he’s worked hard to get himself in great shape. He’s a chance to play consistently at Oldham. I’m looking forward to seeing him back on the field and catching my eye.”