Rossendale tried desperately to come back but it was to no avail leaving the visitors with just a losing bonus point by way of consolation.
Rossendale opened with a try from a penalty line out, a driving maul sucking in the opposition before the ball was spun wide to Aaron Perry his chance in the corner. Lewis Allen slotted the conversion from wide out and added a penalty to give the east Lancashire a 0-10 lead.
Lymm came into the game with a try from Jake Maher converted by Cormack Nolan but coming up to half time a stolen line out and with Dominic Moon finding the space the back rower strolled over to give Rossendale a 7-15 advantage at the interval.
In the second half Nolan reduce the deficit with a penalty and with all to play for both sides went after 'a winner' .
It fell to Lymm who got Giles Dugdale over to level the scorers with Nolan's conversion putting his side in front for the first time with just ten minutes remaining.
Rossendale did their best to come back but failed with a penalty which would have snatched the match.