The Brazilian was standing up to the Cherries’ attack when he received a ball flush in the face.
Josh King was running at the Chelsea defence when he unleashed a deadly shot which hit Luiz and knocked him to the floor.
And the former Paris Saint-Germain man seemed to be out for the count.
He did eventually get up and carry on.
And it was the man who hit him in the face, King, who gave the hosts the lead in the second half.
Fans took to Twitter to react to Luiz’s misfortune.
One fan said: “David Luiz has just got smacked in the mooey and I heard the slap from here tbf. #CFCLive”
Another added: “Ouch. Shot straight to the head of David Luiz.”
A third added: “Poor old David Luiz getting a bullet in the mush seems very popular with a lot of your following. Terrible. (Must admit did a thumbs up myself).”
“If anyone questions David Luiz’s commitment again… show them pictures of that block,” another said.
Antonio Rudiger believes Eden Hazard can help bring the best out of Gonzalo Higuain.
“Everyone who understands football and knows Eden, you can make a profit out of him playing with him,” he told the Evening Standard.
“It [playing without Hazard] is the same as Barcelona playing without [Lionel] Messi. For us it’s Hazard. He can make always the difference, as he showed against Tottenham last week.
“We have to be patient with Higuain. He’s new. Everything’s new. But he will be important for us and he will show his strength.
“First of all, if you see his record, you know he’s a goalscorer. He will do the same here. I’m confident about him.”