The Blues were eliminated from this season's Champions League in the group stage and face Steaua Bucharest in the first leg of the Europa League last 16 on Thursday, before taking on Manchester United in the FA Cup quarterfinals on Sunday.
Luiz reckons the Stamford Bridge outfit could have a slight advantage over the Red Devils, with Sir Alex Ferguson's men still hurting from a controversial European exit against Real Madrid.
"It’s a massive week," Luiz told reporters. "It’ll be difficult again [against Bucharest]. And Sunday [against United] is also a massive game, a game everyone in the world will love to watch.
"I hope we win, because this season it’s not gone as well for Chelsea as last season, so we need to win the titles we’re still in.
"I think it’s difficult [for United] when you’ve been knocked out of an amazing competition like the Champions League. Your confidence is not the same. The happiness inside your heart is not the same.
“Maybe it gives us an advantage. But I know, as well, Manchester United will want to win.
"They’ll play at home but some supporters and some players will be thinking it’s not the Champions League so it’s difficult to come in with the same form."
Luiz also said it is "normal" that the team have gone through a transitional period this season after several recent signings and sales.
"This squad has a lot of quality with many expensive players and young talents," Luiz said. "Some of the guys are becoming a bit old so we needed transition. Manchester United have nine, 10, 11 guys who have played together for a long time.
"Barcelona play together for a long time. Real Madrid needed two years until now to start to become a stronger team. So this is normal."