Bristol Rovers could not win in manager Darrell Clarke's absence as Niall Mason fired Doncaster to a 1-0 victory at the Memorial Stadium.Mason's first-half penalty settled a game in which Clarke could not attend due to a sickness bug. The winner came in the 33rd minute when Tommy Rowe exchanged passes with Alfie Beestin and burst into the box only to be halted by Ryan Sweeney's clumsy challenge.Referee Dean Whitestone pointed to the spot and Mason blasted his penalty down the middle, finding the roof of the net as home goalkeeper Adam Smith moved to his right.Sweeney had Bristol Rovers' best first-half chance, but saw his close-range volley from Liam Sercombe's corner tipped over by Doncaster keeper Ian Lawlor.The hosts almost equalised in the 86th minute when Lee Brown's free-kick was brilliantly saved at full stretch by Lawlor.Rovers forced the ball home in the melee that followed, but a linesman had flagged that the ball had gone out of play and they had to make do with a corner.