Luiz spent two trophy-laden years in Paris with Ibrahimovic after being sold by Chelsea for £50million, winning consecutive trebles before making a surprise return to Stamford Bridge last summer.
Ibrahimovic followed Luiz to England as he joined United on a free transfer, but the Brazilian got the better of the striker as Chelsea thrashed United 4-0 in the league and also oversaw a 1-0 FA Cup win while Ibrahimovic was suspended.
The United star will no doubt want to make his mark against the league leaders this time around, and Luiz says he is ready for the Swede despite acknowledging that the forward has confounded critics with 28 goals in all competitions this season.
Luiz told Chelsea's website: "It is Man United v Chelsea. As simple as that!
"Zlatan is great player, a great personality, everybody was talking bad about him before he came here but he has showed everybody already he has quality.
"I had a great opportunity to play with him, it was great for me, I learned a lot with him and we won a lot of titles but now he plays for Man United and me for Chelsea, and for sure I try my best and he tries his best."
Chelsea need a win to restore their seven-point lead at the top of the table with Tottenham in hot pursuit, and Luiz says the pressure is natural at a club which expects silverware.
"When you play for a big club the pressure is always there," he said.
"If you are at the top, you have pressure and if you are not at the top, you have pressure, so the pressure is always there and you have to know this when you sign for a big club.
"You take this in a natural way and continue to be ambitious to win the league. It is not easy to win the Premier League and we need to focus and keep our feet on the floor.
"I am always excited to do my job and play football, and especially when you have the opportunity to play for a big club with amazing fans, so for me it is always exciting to be on the pitch and even more so if we can give them what they deserve."