Jose Mourinho has made the recruitment of a top-class starting left back one of the priorities of his second summer transfer window at Manchester United. The Old Trafford manager is seeking a physically powerful, quick and aggressive attacking full back to complement Antonio Valencia on the right side of his defence.

One strong candidate for the position is France international Benjamin Mendy, who has proved his worth at Champions League level during AS Monaco’s impressive run to the quarter-finals of this season’s competition. Mendy, who turns 23 in July, was on Mourinho’s list of proposed “supplementary” signings when he was appointed United manager last year.

Monaco, however, had already put a deal in place to bring Mendy from Olympique Marseille for a transfer fee of €13million. Ironically, the individual who drove Monaco’s purchase of the defender was Mourinho’s former chief scout at Real Madrid, Luis Campos.

Though Monaco are open to selling a significant proportion of their highly admired, young squad once their campaign to regain the Ligue 1 title for the first time in 17 years has concluded, their finances are such that they can demand large fees on sales. Mendy is understood to be valued at between €30 and €35m by the principality club.

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View photos Mourinho is searching for a new left-back More

Mourinho’s search for a new left back has been provoked by Luke Shaw’s failure to perform at a level commensurate with his own £30m purchase price – a world record for a full back when Louis van Gaal signed his from Southampton in 2014. The England international has disappointed Mourinho with his mental attitude, long periods in which he applied himself poorly in training, and performances that have failed to match his own technical potential.

The 21-year-old lost his place as Mourinho’s starting left back in early November when he told the Portuguese he was not confident enough to start against Swansea City. “Luke Shaw told me this morning that he was not in the condition to play, so we had to build a defensive line,” explained Mourinho following a win in which Ashley Young and Matteo Darmian were used at full back. “There is a difference between the brave, who want to be there at any cost, and the ones for whom a little pain can make a difference.”

Mourinho has been regularly questioned over Shaw’s five-month absence from United’s Premier League line-up subsequent to the Swansea match. In an attempt to cajole Shaw into performing at a level closer to his potential the Portuguese has commented on his failure to play “the way I like a full back to play” and challenged Shaw to “work better, knowing that I give nothing for free”.

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Before fielding Shaw for the first 70 minutes of a 1-1 home draw with Bournemouth this month Mourinho commented on the improvement in the defender’s physical condition while challenging him to prove he deserved to retain a starting berth. “He needs to show on the pitch the evolution is not just by the physical point of view, but globally,” said Mourinho ahead of the Premier League fixture. “Because a player is globality, not just physical condition.”

Shaw has not played again for United since and it is understood that Mourinho was dissatisfied with the player’s contribution when granted the opportunity to start. “He needs to make the difference, not just deliver the basics,” a source told Yahoo Sport. “The Watford or Bournemouth full back does the basic, not a Manchester United full back.”

Shaw suffered a double fracture of his right leg in September 2015 and last August gave an interview in which he stated that he did not “go a day without feeling it”. His current contract runs until the summer of 2018 with United holding an option to extend for a further year.

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