The Red Devils have been linked with a move to sign Tottenham Hotspur defender Danny Rose over the past 12 months since Mourinho took over the reins at Old Trafford.
Mourinho has helped to transform Antonio Valencia into one of the Premier League’s best right-backs despite starting his career as a winger.
The Red Devils boss has also alternated between Luke Shaw, Matteo Darmian and Daley Blind at left-back amid continued uncertainty surrounding what has become a problem position.
Young, 32, has made the position his own in recent weeks following three goals in their last two victories over Brighton and Watford.
Manchester United signed three players in the summer transfer window but Mourinho didn’t bring in a new left-back.
Former Everton defender Kilbane believes Young is a good enough option at left-back for Mourinho.
“Valencia will be ok for another 18 months,” Kilbane told Irish website Newstalk.
“Ashley Young in fairness to him has got Mourinho’s full trust and he is playing really well.”
Manchester United are in second place in the Premier League table as Mourinho looks to become the first manager since Sir Alex Ferguson to win the title in 2013.
The Red Devils got their hands on the Europa League and the League Cup in their first campaign under Mourinho last term.
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