Bryan Robson has hailed Ander Herrera as a key figure for the club . Manchester United are just four points behind neighbours and rivals City . Ex-United captain Robson recognises Herrera 's qualities and hard work . READ : Why has it taken Louis van Gaal so long to play Herrera ? CLICK HERE for all the latest Manchester United news .
Bryan Robson has hailed Ander Herrera as a key figure for the club . Manchester United are just two points behind neighbours and rivals City . Ex-United captain Robson recognises Herrera 's qualities and hard work . READ : Why has it taken Louis van Gaal so long to play Herrera ? CLICK HERE for all the latest Manchester United news .