It was only Fred's second goal of theseason - and it was the first time since the middle of September that United have recorded back-to-back league wins.
Ansu Fati and Simon Adingra got a goal and an assist each as a clinical Brighton side stunned Ajax 2-0 in Amsterdam to move intothe qualification spots of their Europa League group for the first time.
Toney thought he had broken the deadlock, volleying intothe net from Mbeumo's cross in the 72nd minute, only for the effort to be disallowed for offside.
Diego Costa struck twice to help Chelsea secure a 2-2 draw at Swansea City and ensure the Blues maintained their unbeaten record in the Premier League this season.
Manchester City beat Manchester United 2-1 to extend their perfect start to the Premier League season and end that of their local rivals in an entertaining and action-packed encounter at Old Trafford.