The 31-year-old joined Hoops this summer after his contract expired at Fulham and made an impressive start to life in W12.
However, that came to an abrupt halt on Saturday after Johnson sustained an anterior cruciate ligament injury during the 0-0 draw with west London rivals Chelsea.
It is the latest in a long line of injury blows that have disrupted the former England international's career in recent times, although manager Hughes has backed him to make a successful return. "He was playing exceptionally well at the time and had been in previous games so to lose his experience and ability is a blow to us," he told www.qpr.co.uk.
"People understood why I wanted to bring AJ to the club. He has got fantastic energy and you need those types of players in your squad.
"He is mentally a very, very strong character. He has been through long-term injuries before and always comes back stronger and I have no doubts that he will do the same again.
"He will get the best treatment and best support from the medical staff here and we will make sure we get him back as quickly as possible without ever compromising him.
"We will make sure he is fit and well when he returns."
Source: PA
Source: PA