The Scottish centre's amazing kick - which arrowed over the crossbar from a low trajectory - helped the home side fight back to level the game at 9-9 in the closing stages.

But the unbeaten Chiefs had the final say when Chris Budgen powered over from close range on 77 minutes to maintain the visitors' impressive 100 per cent record.

Knights showed plenty of power and endeavour but their kicking game continually let them down as Exeter took a 6-0 lead through two Gareth Steenson penalties.

Ali Warnock halved the deficit with a penalty on the half hour but they again found themselves six points behind at the break when Matt Cornwell slotted over a neat drop goal.

Doncaster's resolute defending kept the Chiefs' at bay during a period of intense pressure at the start of the second period before McColl had the Castle Park crowd on its feet with his superb kick from five yards inside his own half.

Warnock's drop goal briefly levelled a hard fought encounter but Budgen won it for the visitors in the dying moments.

Doncaster: McColl, Briers, Tonga'uiha, Armitage, Williams, Warnock, Hallam, Davies, Boden, Tau, Griffiths, Townson, Cochrane, Grainger, Planchant. Replacements: Cusack, Lawrie, Corsar, Boyde, Kettle, D'arcy, Carter.