Roberto Di Matteo has described the pair as "very doubtful" for the weekend fixture, and has also ruled out Frank Lampard.
Roberto Di Matteo had some injury updates for us on Friday ahead of tomorrow's game in Wales. According to Di Matteo, both Juan Mata and David Luiz are "very doubtful" to play against Swansea due to injury:
Chelsea FC (@chelseafc) November 2, 2012
He also had an update on Frank Lampard:
RDM says next Wednesday's game v Shakhtar will be too soon for Frank Lampard to recover from his calf injury. #CFC— Chelsea FC (@chelseafc) November 2, 2012
Lampard being ruled out comes as no surprise, and we'll likely see a starting pivot of John Obi Mikel and Ramires for the game. Juan Mata has been in excellent form, but if he's unable to play we should still be fine with all of Victor Moses coming off of a great game and Marko Marin supposedly healthy.
David Luiz is a bit more concerning, as John Terry will be serving the final game of his suspension on Saturday. If unable to play, we're looking at a center back pairing of Branislav Ivanovic and Gary Cahill, with Cesar Azpilicueta starting at right back. That's not the worst thing in the world, but it's a lineup we haven't seen previously.
Neither player has been ruled out officially, so we'll have to wait until tomorrow to see what happens. Get well soon though guys, we'll need you against Shakhtar on Wednesday.