By Sean Walsh Manchester United could be left alone in the race to sign Joshua Zirkzee as AC Milan are now looking at other strikers instead, with Romelu Lukaku an option, a report has claimed. 90min first revealed back in January that Zirkzee was firmly on United’s radar ahead of the summer transfer window. Reports from all over England and Europe claimed last week that the Red Devils were advancing their interest in the Bologna striker. Milan have also spent much of June in contact with Zirkzee’s entourage. His contract contains a relatively affordable £34m release clause, but personal terms…