Castleford (4) 8
Harlequins (6) 12
Dorn moved from Castleford to Harlequins in the close season
Luke Dorn marked his return to Harlequins with a try either side of the break to help them to victory over Castleford at The Jungle.
The Tigers led through a James Evans try until just before the break when Dorn's interception try, converted by Rob Purdham edged them ahead.
Dorn then latched on to Danny Orr's kick to score his second try less than a minute into the second half.
Richard Owen's late score was little consolation for the Tigers.
Castleford coach Terry Matterson:
"We've got to take the positives out of the game. I thought that we gave a really good defensive performance.
"But we're here to win and we didn't win today so we're disappointed.
"We've worked hard on our attack as well but we've got a lot of work to do."
Harlequins coach Brian McDermott:
"I thought Castleford had a lot of dominance in the first half and they carried it but we answered every question they asked.
"I thought for a first game, it's probably not the most skilful game you'll see but in terms of two sides going at it hammer and tongs I thought it was very good.
"All cliches aside, we're here to win, we came here to win and that what we did."
McGoldrick, Dixon, Evans, Shenton, Owen, Faumuina, Chase, Sargent, Hudson, Higgins, Ferres, Jones, Westerman.
Huby, Feather, Netherton, Widders.
Wells, Melling, Gafa, Howell, Sharp, Dorn, Orr, Temata, Randall, Ward, Williamson, Robinson, Purdham.
McCarthy-Scarsbrook, Haggerty, Kaye, Clubb.
J Leahy (Dewsbury)