Shock title challengers Girona dropped two vital points in La Liga with a 0-0 draw against Real Sociedad on Saturday.
The Catalan minnows, second and now trailing leaders Real Madrid by one point, could not find a way through against their Basque visitors.
Los Blancos face city rivals Atletico Madrid on Sunday at the Santiago Bernabeu and can potentially move four points clear at the top.
Girona's draw leaves them six points ahead of champions Barcelona, third. Despite leading the league in goals scored, Michel Sanchez's side were largely kept at arm's length by La Real.
Alex Remiro made a solid save to deny Herrera in the final stages as the hosts were frustrated and Michel was sent off for complaining on the touchline.
Valery Fernandez missed a fine chance in stoppage time after Yan Couto scrapped hard to win the ball back and crossed for the Spanish winger.
Without La Liga's joint top goalscorer Artem Dovbyk, who watched from the stands after suffering knee discomfort according to Spanish reports, Girona did not shine in attack.
When they did put the ball in the net through Herrera, after Savinho cleverly scooped the ball to him at the back post, officials ruled the goal out because of an offside 36 seconds before during build-up play.
Girona will have the chance to make amends next weekend when they visit Real Madrid in a crunch showdown.
However coach Michel will not be in the dugout, while Herrera and Daley Blind were both booked and are also suspended for the key clash.