Luiz still has title belief
Chelsea, the 2012 winners, will play Atletico Madrid in the Champions League last four after overturning a two-goal deficit to Paris St Germain.
Domestic duty is the immediate priority, with Sunday's match at Swansea as Chelsea bid to keep pace at the top of the table with Liverpool and Manchester City, who meet at Anfield on the same day.
"It's still possible to win the league, so come on, let's enjoy the position we are in and believe, like we did against Paris St Germain," Luiz said on chelseafc.com.
"We need to have faith because we can still do it.
"Mathematically it's still possible but every game in the Premier League is difficult, as it will be on Sunday.
"Swansea are tough opponents and we've seen in the last few seasons, every time we go there it's a difficult game.
"We need to try to do our best and win the match."
Luiz has struggled to break into Jose Mourinho's first-choice defence but instead has convinced the manager to field him in defensive midfield, performing with aplomb.
The Brazilian said: "Everybody knows when I'm on the pitch I give everything and play with my heart, but everybody played with the same spirit.
"I watched the (PSG) game back at home afterwards and it was fantastic to see every player working hard, wanting the ball and helping each other.
"I was happy with my performances in both legs; when you win people look at the game in a different way but that's football, it's about results, not performances."
Looking ahead to the April 22 trip to Atletico, Luiz stressed the importance of a strong showing in the first leg.
"It's always good to play the second leg at home, but only if you do well in the first leg," he added.
"If not, your heart can stop, especially if it's like the matches in Paris and Napoli (in 2012), we don't want that to happen again.
"You cannot choose who you play, all four sides are great teams, that's why they are in the semi-finals.
"Atletico are a top team, they beat Barcelona, they're top of the league and they have a great manager.
"Their philosophy is a good one and it will be a tough game, but I love big matches, I love the pressure and the responsibility it brings, so I'm looking forward to it."
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