Arnautovic has established himself as the key player at West Ham in Manuel Lanzini's absence.
With four goals so far this season the Austrian has continued his great form in 2018 which has seen him involved in more Premier League goals than anyone else except Mo Salah.
But in the last couple of months West Ham fans have been left wincing everytime Arnautovic goes down on the floor as he has been playing with a mystery knee injury.
The injury has seen the striker withdrawn from a number of matches although he completed the 90 minutes in the 1-0 defeat to Brighton last time out.
Despite the issue Arnautovic has made himself available for international duty with Austria.
Fans - and privately probably Manuel Pellegrini too - are understandably concerned their star man could aggravate the issue over the international break when a couple of weeks' rest may have come at the perfect time.
And now speaking to Sky Sports, the striker has revealed the full extent of the injury for the first time, but insists he wants to play on through the pain barrier.
"The knee is not the best, I'm fit, I can play, but I'm not training a lot, also at West Ham and I try to recover my knee," Arnautovic told Sky Sports.
"It's going to take some time, I've got some inflammation in my bone but I am always ready to play on the weekend so it's just one of those things.
"Obviously after a game I need some rest, like two or three days, but then middle of the week I am training normal with the team and training full and on the weekend I play, that's the most important thing.
"Obviously you can't do anything on this bone bruise, you can't change it, you can't do nothing, you just have to treat it good, you have to settle it down but I can handle the pain so for me, for the games I'm 100% fit."
It is worrying times for West Ham the next two weeks.
Supporters will undoubtedly be hoping Arnie returns unscathed for their huge game against fierce rivals Tottenham when the Premier League resumes.
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