Liverpool scored two late goals - including a dramatic injury-time winner from Sadio Mane - as they came from behind to beat Aston Villa and preserve their six-point lead at the top of the Premier League.With their 10-month long unbeaten league record seemingly about to end, the Reds dug deep to conjure a stellar finish, begun when Andy Robertson arrived at the back post to head them level.Mane then provided the final, remarkable twist, glancing a header from Trent Alexander-Arnold's corner past Tom Heaton and into the far corner of the net.It was a cruel blow to Villa, who had led from the 21st minute through summer-signing Trezeguet's first goal for the club - a volleyed finish from John McGinn's free-kick.The home side had shown huge endeavour, in a display that saw them match the European champions in the first half and then hold them largely at arm's length until the dying moments of the second.Liverpool's win means they retain their advantage over second-placed Manchester City, who staged their own comeback to beat Southampton and visit Anfield for a mouth-watering top-of-the-table clash next Sunday.Having won two on the bounce earlier this month, Villa have now lost back-to-back games - admittedly to the league's top two sides - leaving them in 16th place, three points above the relegation zone.