Chelsea are "sending a clear message" to their players that they cannot rest on their laurels after making a flurry of signings, according to central defender Antonio Rudiger.

Frank Lampard's men made their fourth signing of 2020 on Thursday with the arrival of French youngster Malang Sarr on a free transfer following his exit from Ligue 1 club Nice.

Chelsea, who finished fourth in the Premier League last season, have also added Hakim Ziyech, Timo Werner and Ben Chilwell to their squad ahead of the 2020-21 campaign.

Experienced centre-back Thiago Silva and Bayer Leverkusen forward Kai Havertz have also been tipped to join the Blues before the new season starts next month.

Despite the added competition for places, Rudiger insists he is pleased with his side's transfer business to date. 

"I am always happy to see new faces in the team," he 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."

Chelsea won just four of their final seven league matches and finished 33 points behind champions Liverpool, while runners-up Manchester City were 15 points better off.

And while Rudiger is realistic about his side's targets for the new campaign, he does not expect last term's top two to continue having things all their own way.

"What Liverpool and Man City have shown over the past few years, you have to take your hat off to them," he said. "That has my greatest respect. 

"But I don't expect these two teams to dominate everything for the next few years. Man United could move closer in the long term with consistent performances like after the corona break, and we shouldn't forget Tottenham. 

"And then there's also us, who want to close the gap step by step.

"That will certainly be a big challenge. We don't want to set something like this as our direct target. We simply want to be even better than last season, in any case to get closer to the best teams in Europe. 

"We've already shown we can keep up with the best in single matches. What's missing is consistency throughout the season. But that is normal for our relatively young squad."

Rudiger started 25 games for Chelsea in all competitions last season and is happy to take on more responsibility following the departure of some experienced players.

"I feel extremely comfortable and also valued," he said. "My role has changed, especially in the last year, because we lost a few experienced players like Eden Hazard or David Luiz and a lot of young players have moved up. 

"All of a sudden, I was the player who was almost among the older ones and therefore had to take on more responsibility off the pitch as well. But I love doing that and it helps me in my development."