Will Buckley scored for the second successive Championship game as Brighton won at Peterborough to remain in touch of the play-off places.
Buckley netted both his team's goals at London Road, grabbing his first after a mistake by goalkeeper Joe Lewis.
Peterborough substitute David Ball equalised from close-range, giving the hosts hope of a draw.
But Buckley bagged the winner with a clinical finish from the edge of the penalty area.
Changes were inevitable for Brighton after they were taken to extra-time and penalties by Wrexham in the FA Cup in midweek, and boss Gus Poyet made four.
But Brighton looked fresh and created chances from the start, with Matt Sparrow and Craig Mackail-Smith each coming close.
The visitors eventually went ahead after Sinclair fouled Adam El-Abd wide on the left, and Buckley floated the resulting free-kick over Lewis's head into the net.
Peterborough responded well and Peter Brezovan had to get down to deny Sinclair before Ryan Tunnicliffe sent a shot over the crossbar.
Sparrow threatened again early in the second half but Posh were soon on the offensive again and Taylor tested Brezovan with a 20-yard drive.
Ball levelled after 72 minutes, scoring from close range after being teed up by Tunnicliffe.
It looked like that would be enough to earn a point but, with two minutes remaining, Buckley beat Lewis with a drive from the edge of the box that flew into the roof of the net.