The 22-year-old was sent off in Sunday's 1-0 defeat to Valencia for raising his arm into the face of Hugo Duro in the closing stages of a game that was marred by alleged racist abuse aimed at the Brazilian, with the contest at the Mestalla stopped for 10 minutes midway through the second half.
Vinicius, who claims "racism is normal in La Liga", will now serve a two-match suspension, while Carlo Ancelotti could also be without injured duo Eden Hazard and Mariano Diaz, who missed the last match with respective ankle and thigh problems.
Real Madrid goalkeeper Thibaut Courtois was fit to start against Valencia after sustaining a minor tricep injury in last week's Champions League semi-final second-leg loss at Manchester City, and the Belgian is expected to retain his place between the sticks on Wednesday.
Dani Carvajal will be pushing for a recall at right-back ahead of Lucas Vazquez, while David Alaba could also return to defence at the expense of either Antonio Rudiger or Ferland Mendy.
Experienced duo Luka Modric and Toni Kroos, who are both allegedly set to sign new contracts at the Bernabeu, came on as second-half substitutes last time out but could be handed starts in centre-midfield against Rayo Vallecano, with Dani Ceballos and one of either Aurelien Tchouameni or Eduardo Camavinga potentially dropping to the bench.
In the absence of Vinicius, Brazilian compatriot Rodrygo is expected to start on the left flank, while either Marco Asensio or Federico Valverde is set to operate on the opposite wing in support of central striker Karim Benzema.
Real Madrid possible starting lineup: Courtois; Carvajal, Militao, Rudiger, Alaba; Kroos, Tchouameni, Modric; Asensio, Benzema, Rodrygo