Boss Lynn Howells handed starts to long term injury absentees Anthony Carter and Chris Planchant as he rotated his squad for the Castle Park clash.

And the pair were both influential as Doncaster ran out comfortable winners against their visitors from north of the border.

The impressive Hudson Tonga'uiha took just seven minutes to break the deadlock when he powered over from close range for an unconverted try.

And Planchant got in on the act midway through the first half when he broke from a maul to cross the line and give Ali Warnock the chance to make up for his earlier miss.

Ayr ended the first period on top but Doncaster held firm and virtually made the game safe with two Warnock penalties on 49 and 57 minutes.

Speedy winger Matty Williams then added his name to the try sheet on the hour when he superbly collected Tonga'uiha's neat chip and ran in between the posts to give Warnock a simple conversion.

The visitors hit back with a late consolation score through Steven Adair, with Mark Stewart adding the extras.

But the day belonged to Doncaster and the home side increased their lead five minutes from time when Warnock converted his own try after he intercepted a pass and was left with a clear 20-yard run to the line.

Knights travel to Welsh Premiership side Pontypridd on Friday night for their second Pool D game.

Team: Carter, Flockhart, Briers, Tonga'uiha, Williams, Warnock, D'Arcy, Davies, Lawrie, Cusack, Griffiths, Townson, Boyde, Cochrane, Planchant.