West Ham coach Slaven Bilic has described Marko Arnautovic as a "massive player" following his switch from Stoke City.
Arnautovic joined West Ham from Stoke in a club-record deal worth up to £25million on Saturday.
The acquisition of the Austria forward follows those of defender Pablo Zabaleta and goalkeeper Joe Hart, while the club have been heavily linked with a move for Bayer Leverkusen and Mexico striker Javier Hernandez.
And Bilic expects Arnautovic to quickly adapt to life with the Hammers, telling the club's official website: "It's a great thing for the club. It's a big signing - he is a massive player who knows the league, which is very important.
"He is in his best age, he is very motivated and I know him very well. He is a top player and he can play all across the front line, so he is a great signing for the club.
"Like everybody else he has to prove himself, but I expect him to and he comes into the category of players who don't need to adjust a lot to the league because he has been here for four years.
"He became one of, if not the, best and most important Stoke players. Stoke is good club, so with all that and knowing that today it's not easy to get top players, it makes it a great signing for us.
He's a Hammer! pic.twitter.com/oEJ79wPnvu-- West Ham United (@WestHamUtd) July 22, 2017
"I said at the end of last season that we don't need squad players, but we need top players, the players who are going to improve the first XI, and when I say the first XI that means the 14 or 15 you need for that game and the game after.
"The players we have brought in are those kind of players. Joe Hart, Pablo Zabaleta and Marko Arnautovic, they are the players who can bring the quality to our team.
"Then with those players, the young ones will flourish because they are going to learn from them and it will ease the pressure on them.
"Now, the majority of that is done, so congratulations to the chairman, to the board. They have done brilliantly and people from other clubs have recognised it.
"You never know how it is going to click, but we can for sure say we have done well. Also, it is important that we have done it early enough in the transfer window.
"It's a massive achievement - it's not easy, but we have done it."