Adrian Gonzalez had given Racing a second-minute lead at the Sardinero but the introduction of striker Aduriz in the 63rd turned the game for the visitors.
The substitute volleyed in from a corner four minutes later and poached a second goal with an opportunist header before Bernardo rose to head Zaragoza level two minutes from time.
Tempers boiled over at the end with the hosts having Pedro Munitis sent off while Ricardo Costa was dismissed for Valencia who finished with nine on the pitch as Mehmet Topal left with a head injury after all their substitutes had been used.
Valencia have 36 points from 20 games, nine behind second-placed Barcelona who they host in a King's Cup semi-final first leg on Wednesday.
Levante, fourth with 31 points, lost 2-1 at home to Getafe.
Former Spain striker Dani Guiza opened the scoring for the visitors with a lucky rebound and Diego Castro doubled their lead on a breakaway in the 83rd. Ruben Suarez pulled one back for the hosts from the penalty spot at the end.
They retain the last Champions League qualification berth on goal difference from Espanyol in fifth.
FEISTY DERBY
Qatari-owned Malaga climbed to seventh on 28 points with a typically feisty 2-1 home win over regional rivals Sevilla, their first in La Liga since November.
All the goals came in the first 20 minutes, with Weligton and Sebastian Fernandez giving the hosts the lead either side of Antonio Luna's reply for Sevilla, and they held on despite losing Isco to a red card in the bad-tempered closing stages.
The win had normally placid coach Manuel Pellegrini punching the air at the final whistle as the Rosaleda breathed a collective sigh of relief.
New Granada coach Abel Resino made a good start as his side won 2-1 in another Andalucian derby at Real Betis in the midday kick-off.
First-half goals from Nigerian striker Ighalo and Portuguese midfielder Carlos Martins helped drag the promoted side out of the bottom three up to 16th with 22 points.
They are ahead of Racing on 21, Villarreal with 20, Sporting Gijon who have 18 and basement side Real Zaragoza on 12.
Sporting were hammered 5-1 at mid-table Real Sociedad after David Zurutuza scored twice in the first four minutes before having to be substituted after a clash of heads in the seventh. He was taken to hospital for surgery on a broken nose.
The Basques wrapped up the win with three more goals in the last 14 minutes.
