Chelsea manager, Frank Lampard, has been warned by Paul Merson, that David Luizās departure to Arsenal will come back to haunt him.
Luiz left Stamford Bridge to sign a two-year deal with the Gunners on transfer deadline day.
Lampard began his reign in charge of the Blues, with a 4-0 defeat to Manchester United in the Premier League on Sunday.
Kurt Zouma, who started in the centre of defence, gave away a penalty in the first half, which Marcus Rashford scored to make it 1-0.
The France defender was generally shaky and Merson, speaking to Sky Sports, insists Luiz was Chelseaās best ball-playing defender.
āFrank Lampard has got to be careful. Chelsea have let their best ball-playing defender leave to go to their rivals, not just in London but in the top four. None of their defenders can play out from the back.
āI can understand if Chelsea pushed everyone up to the halfway line, the goalkeeper kicks it, and they play in the other half, but if youāre asking them to start playing out from the back, theyāre going to get beaten left, right and centre.
āKurt Zouma just didnāt look ready. He didnāt look ready before this, which is why he went out on loan. Itās a dangerous, dangerous game. The fans liked David Luiz. They need to get results quickly, because the fans wonāt be happy watching them play out and lose the ball.
āIt looked like Frank looked at the situation and thought: āI need it quiet here, I canāt be having problemsā, so Chelsea let Luiz go. Sometimes thatās the way it is, and great managers have a high-maintenance player and get them to perform.
āI go to Stamford Bridge a lot, and Chelseaās defence are asked to play out nearly all the time. Kepa doesnāt kick anything long. Luiz was the best player on the ball by a million miles. Now all of a sudden youāve got players who canāt play out, and teams will suffocate them.
āFirst 45 minutes, Chelsea looked good but didnāt have that cutting edge. Tammy Abraham will take time; heās been playing a lot in the Championship, and thatās where youāll pick up bad habits. He would have had six chances in most games in the Championship.
āMason Mount is a tidy player, and heāll get better as time goes on. But it absolutely blew my mind when NāGolo Kante came on at 3-0 down. What for? If heās fit enough to play, play him. If heās not, why bring him on with 20 minutes to play? You may as well say to him: āWait there, youāll have another week training and get ready for another very, very big game on Sunday against Leicester.ā I was very surprised with that.
āItās not just getting beat 4-0, itās the way they were beaten. This is a different job for Frank, heās now managing one of the biggest clubs in the country. He will learn, and you only learn from experience,ā he said.