The Spain defender was sent off for a club record 18th time just before half-time in Real's 2-2 draw at Estadio El Sadar on Saturday, but the Spanish giants appealed against the decision.
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Ramos' first yellow card was shown for a foul on Alvaro Cejudo, but the Spain Football Association's disciplinary committe agreed that there was no contact and so the former Sevilla man will not serve a suspension.
A statement on Real's official website said: "The Spanish football association's disciplinary committee has decided to overturn the first yellow card that Sergio Ramos was shown in the last match against Osasuna.
"He will be available for selection by the coach Carlo Ancelotti in the next league fixture, when Real Madrid play Valencia on Sunday.
"After accepting the video evidence provided by the club, the committee ruled that 'there is no contact likely to cause a player to fall,' and so they ruled that 'the first yellow card and the subsequent red card for receiving two yellow cards should not count for disciplinary purposes'."
The news comes as a major boost for coach Carlo Ancelotti, as his side look to close the five-point gap to leaders Barcelona and second-placed Atletico Madrid.