Mourinho has been heavily linked with the Old Trafford club as Van Gaal comes under increasing pressure, and has suggested he will be back in management soon.
And the former Chelsea centre-back, who was sold to the Blues' Champions League last 16 opponents while Mourinho was in charge at Stamford Bridge, would not be surprised if the Portuguese joins United in the near future.
“Coaches come, coaches go, it’s part of football,” Luiz told reporters. “Jose won't be out of work for long, he never is.
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"You can’t dispute the success he has had - that is why I am sure Manchester United are looking at him.
“I don’t think Jose would have any problem taking the Manchester United job. Yes, he will always care for Chelsea, but Jose does what is best for Jose.”