Antonio Rudiger says Chelsea's new arrivals will force the first-team squad to step up their game.
Frank Lampard has brought in Malang Sarr, Ben Chilwell, Timo Werner and Hakim Ziyech; while Thiago Silva and Kai Havertz are also expected to join.
And Rudiger admits he and his teammates have been put on notice by manager Frank Lampard.
"I am always happy to see new faces in the team," Rudiger told Transfermarkt.
"After the transfer ban last summer, we were of course hoping to get some real reinforcements. With Hakim, I immediately had a good feeling and my relation to and opinion about Timo is already known.
"With such names, the club is also sending a clear message to the existing personnel that they want to take another step forward in the overall development. I think that is great!"
