The Southampton boss has heaped praise on the 26-year-old.
The Saints head coach admitted he was worried about the striker's fitness but says he will be in the Southampton squad to face Manchester United this weekend.
Austin scored 18 goals for QPR last season and has no doubt been brought to Southampton with hope of a similar return.
The Dutchman told reporters ahead of this weekend's Premier League clash against Manchester United: "I was a little worried because Charlie had a hamstring injury before we signed him but he had all the medical tests and took part in all the training sessions this week.
"We had to test him to know he is available and on his fitness tests he is as good as the rest of the players. I wasn't expecting it so quickly but it's nice to be surprised. He will be in the squad this weekend."
From playing Championship football to being in the running to face Manchester United within the space of a couple of weeks - that's good going for any striker.
But it's nothing less than Austin deserves. At QPR, the 26-year-old has scored goals galore and there is no questioning his goalscoring ability.
It appears the majority of the doubts from Premier League clubs were centred around Austin's fitness but that's something he can address during his time at Southampton.
A goal against United would be some way to introduce himself at St Mary's. But let's see what happens...