Last season, Arnautovic struck 11 times in 35 games to help West Ham overcome a dismal start to the season - even if he had a tricky start to life with the club when he was sent off in just his second league game.
The Austria global has scored eight goals in 17 matches this season having moved from Stoke City to the Hammers in 2017 for around £20 million.
They bought him to keep them in the Premier Leaguelast season and he did that.
Arnautovic's brother Danijel, who also acts as his representative, revealed that the player wants to leave and urged West Ham to sell.
West Ham manager Manuel Pellegrini has hinted that Samir Nasri could be in line to make his Premier League debut against his former club after the 31-year-old played 58 minutes of West Ham's 2-0 FA Cup third round win against Birmingham.
However, they now have no room on their roster to sign foreign players, suggesting they may not be the club in question. "They paid £20m for him, which is nothing in the current market", read a statement from Danijel to talkSPORT. Saturday is a new challenge.
A Chinese Super League club, believed to be champions Shanghai SiPG, are understood to have launched a £35million swoop for Arnautovic, the Hammers' top scorer. "This is what he wants".
"It's not like it was when it was all lads who came from within an area, played for West Ham, that was their club and they were all happy to be there". It is close to double what they paid for him.
West Ham signed Arnautovic for a fee that rises to £25m from Stoke City in July 2017.
While some Hammers seem adamant that Arnautovic won't leave during the January transfer window, a plethora of fans have fired into the Austrian amidst the transfers rumours, and here's a flavour of what some of the fans have said about these recent goings-on and many have likened this situation to that of the Dimitri Payet saga. Marko in this moment is a player of our team, players of his quality and other players like Declan Rice, Felipe Anderson, other clubs will want them but that is one thing.
Marko is professional and is preparing himself for the Arsenal game.
"They come and they go", he told the Alan Brazil Sports Breakfast.