Brazilian defender David Luiz made a surprise switch from Chelsea to Arsenal on transfer deadline day for a fee believed to be around £8 million.

Arsenal needed a replacement for Laurent Koscielny, who left the club for Bordeaux, and they found that replacement from the Chelsea team.

After Chelsea’s 4-0 defeat to Manchester United, pressure has been heaped on Blues boss Frank Lampard, and his decision to let the Brazilian go has earned him criticisms from all corner.

Sky Sports pundit Paul Merson has warned Lampard to be careful and insists that Lampard must look for a solution, admitting that Luiz is the team’s best ball playing player.

Merson said: “Frank 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.

“Kurt Zouma just didn’t look ready. He didn’t look ready before this, which is why he went out on loan. It’s a dangerous, dangerous game. The fans liked David Luiz. They need to get results quickly, because the fans won’t be happy watching them play out and lose the ball.

“I go to Stamford Bridge a lot, and Chelsea’s defence are asked to play out nearly all the time. Kepa doesn’t kick anything long. Luiz was the best player on the ball by a million miles. Now all of a sudden you’ve got players who can’t play out, and teams will suffocate them.”