Red-hot Jack Marriott hit a second-half double as Peterborough continued their perfect League One start by beating Rotherham 2-1.The B£450,000 striker took his tally to five goals in two games when hitting the opener and winner in an ABAX Stadium thriller.Marriott fired Posh ahead two minutes into the second half with a low shot that crept in courtesy of a kiss off the inside of the far post.But Rotherham were soon back on level terms as Kieffer Moore, who like Marriott hit a hat-trick in his previous league appearance, headed in captain Lee Frecklington's left-wing cross.Marriott then steered a Marcus Maddison cross against a post to be denied by the woodwork for the second time after seeing an early effort hit the underside of the crossbar.Rotherham thought they had hit the front moments later only to see their celebrations cut short by a raised flag when Jamie Proctor nodded in from close range.But a cracking contest was settled with 15 minutes to go when Marriott got the better of dithering defender Semi Ajayi and lobbed a glorious finish over stranded Rotherham goalkeeper Richard O'Donnell.