The only one who knows for certain what the lineup will be is Boudreau, but we've also seen line combinations in practice and again today for the morning skate -- although some players elected to take their option and not hit the ice this morning.
Part of the reason you might see Chimera up top rather than someone like Laich, is Boudreau often stresses the importance of having balance among his forward lines. Shifting Chimera up and putting Fehr in on the third unit minimizes the overall change in the lineup, not to mention Laich can take important faceoffs where Johansson may not be the ideal choice.
We'll post the lineup the Capitals skate during warm-ups later today, but based on practices it could look like: Ovechkin-Backstrom-Chimera, Sturm-Arnott-Semin, Laich-Johansson-Fehr, Hendricks-Gordon-Bradley.