Ed Malyon of the Daily Mirror reports that Luiz was seen limping toward the bench after the break:
Crystal Palace confirmed a switch was made, as Chelsea brought on Oscar:
Luiz suffered a knock in the first half. It initially looked like the defensive-minded veteran would be able to continue, but apparently, after further evaluation at halftime, it was decided that the best option would be to have him subbed out for the final 45 minutes.
The severity of the ailment is unclear pending further word from the Blues. If Luiz is forced to miss time at such a crucial point of the campaign, manager Jose Mourinho will certainly miss his versatility as the club chases the Premier League title.
He's played both as a central defender and defensive midfielder throughout the campaign. The Brazilian international is a solid contributor in both roles, appearing in 17 Premier League fixtures.
More information will be provided about his status as it becomes available.