David Luiz credited new Arsenal coach Mikel Arteta with bringing "fun" back to the club, suggesting the squad had become "sad" under his predecessor Unai Emery.
Arteta replaced Emery in December having spent a spell as Pep Guardiola's assistant at Manchester City, with the club becoming underwhelmed by the team's direction under the previous coach.
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Although Arsenal have only won three of Arteta's nine matches in charge across all competitions, the 2-1 loss to Chelsea is their solitary defeat in that time – in the previous nine outings the Gunners were beaten four times.
For David Luiz, the changes implemented by Arteta have improved the mood of the players, while he also applauded the former Arsenal midfielder for the style of play he is attempting to impose.
"If you sleep four hours happy, you're going to sleep better than eight hours sad," the Brazilian wrote in a column on Arsenal's official website .
"It's like I said in that interview, and I stand by it. The result of people when they are happy is 10 times better than when they are sad. For me, you have to have fun not just in football, but in life. That's the most important thing – and Mikel Arteta has brought that back.
"Working with Mikel has been great since the first day. He's always working straight to the point and he has already shown us his ideas, his goals. He wants to try to bring the shine back to this club with a winning mentality and by working hard every single day.
"He's trying to do everything as well as possible to achieve that. For me, personally, I'm enjoying it a lot. I came from clubs that would always fight for titles and would always fight to win, and Mikel knows that as well.
"He had an opportunity to go to amazing places and different clubs, and he worked a lot as an assistant coach for Pep Guardiola. He learned in the best way, so I think for sure he will be one of the best soon.
"His philosophy is the way I love to play football and that makes it easy for me to adapt to. We try to dominate and control possession and try winning the ball back as soon as we lose it.
"This is the idea I really love when I play football. I think Mikel is just trying to organise us every single day in the details, to make the quality of our work even better.
"It doesn't matter if it's his first job as a coach or not. He knows football, he knows inside the pitch. He prepared himself outside the pitch and he's ready for that.
"I've had the opportunity to work with many, many coaches already in my career and I think he's more than prepared to do the job. The enthusiasm comes naturally when you love something. He loves football, he loves to work, so this enthusiasm is contagious for everybody."
After 25 matches, Arsenal are 10th in the Premier League, 10 points adrift of Chelsea in fourth.