Energy company Powergen has decided to end its sponsorship of rugby union and rugby league's leading domestic cups to concentrate its resources on football.
Two weeks ago Powergen's parent company E.ON was named as the new title sponsor of the FA Cup on a four-year deal.
"The deals came to a natural conclusion for us as a business," said Powergen's head of sponsorship Mike Thompson.
As a result, rugby union's Anglo-Welsh Powergen Cup will need restructuring just one year into its existence.
The new Powergen Cup has proved popular with fans and broadcasters, but has been affected by club v country disputes.
However, the Rugby Football Union and Premier Rugby - the English clubs' umbrella body - said Powergen had helped the competition become a great success.
"Our focus now is to find a new partner who will be as committed as Powergen so that we can continue to have exciting competitions across all levels of the game," said RFU business operations director Paul Vaughan.
Rugby Football League chief executive Richard Lewis said he was sure the Challenge Cup would prove attractive to potential new sponsors.
"We believe that the Challenge Cup is a massively prestigious tournament that will prove to be a highly attractive sponsorship property for major brands in the future," he said.
"It inspires great passion from supporters and generates a great deal of wider interest and we believe that becoming the tournament's next major partner will prove highly attractive."