Billy Davies went into the game against the bottom of the table Glovers without the services of Henri Lansbury and Danny Collins through suspension and injury respectively.
The Scot recalled Eric Lichaj following his suspension while starts for Jamaal Lascelles and Nathaniel Chalobah completed three changes from the XI that took to the field for the Bournemouth game.
Yeovil were without on-loan Winger winger Fraser Fyvie while last season's top goalscorer Paddy Madden returned to the squad after missing out completely against Brighton last weekend.
The hosts took an early lead through Upson, the goal after 7 minutes only their 7th of the season in the league to date. Cox then missed a penalty for the Reds before Upson added another on 40 minutes.
Chalobah netted for the Reds but any hopes that would spark a fightback were swiftly extinguised as Webster made it 3-1 to Yeovil at the break.
Chalobah, who had been shown a yellow card in the first-half, stayed in the dressing room to be replaced by Dan Harding for the second 45 minutes. Paterson and Mackie also entered the fray but, despite 27 attempts and 13 on target for the visitors they could not add to their tally and slipped to a disappointing defeat.