Warrington Wolves moved up to second in the Super League table after easily beating Crusaders on Sunday while St Helens' three-match winning run was ended by mid-table Hull KR in spectacular fashion.
The Robins surged into a 16-4 lead after only 24 minutes only for the visitors to cross for three tries in ten minutes to take a 20-16 advantage in to the interval.
Liam Colbon's third try of the afternoon in the 47th minute handed the advantage back to Rovers only for Chris Dean to restore St Helens' advantage before the hour mark.
St Helens looked set to hang on to their 24-22 advantage as there were no points scored for 21 minutes before Ben Fisher went over for a 77th-minute try that ultimately proved conclusive.
Meanwhile, Warrington ran in eight tries as they romped to a 46-12 victory against Crusaders.
The Welsh side actually led 12-6 after 17 minutes but fell away badly as Matt King and Ben Westwood both scored two tries for Tony Smith's in-form side.