Madrid started well and dominated the opening 20 minutes but Valencia grew as the game went on and went ahead through Carlos Soler late in the second half.
It looked like Zinedine Zidane's side were heading for defeat until a corner deep in added time, when goalkeeper Thibaut Courtois' header was saved by Jaume Domenech only for Benzema to pounce and save the point.
Madrid's start to the game suggested that once again they are stronger with a midfield four rather than their traditional 4-3-3. Casemiro may have been rested but Fede Valverde, Toni Kroos, Luka Modric and Isco were fundamental in controlling possession early on.
They struggled after that and lost their way, but never gave up. Benzema's late goal changed everything and means Madrid aren't at a disadvantage, psychologically or in terms of points, going into El Clasico at Camp Nou on Wednesday.
Madrid started strongly but were unable to capitalise, fading as the first half went on. Picking Casemiro -- one yellow card away from suspension for El Clasico -- would have been a huge gamble from Zinedine Zidane, and one the coach didn't take. Unfortunately there is no other player in the squad who can perform his defensive midfield role to the same level and the Brazilian was missed for Valencia's goal.
Manager rating out of 10
7 -- Zinedine Zidane made seven changes from the team that beat Club Brugge 3-1 in Belgium in midweek. His key decisions -- picking Nacho at left-back, resting Casemiro, and choosing Rodrygo to partner with Benzema -- looked to have paid off early on. When the game drifted away from Real Madrid, Zidane reacted -- introducing Bale, Vinicius and Jovic -- before being saved by Benzema.
Player ratings (1-10; 10 = best. Players introduced after 70 minutes get no rating)
GK Thibaut Courtois, 7 -- The Belgian keeper could have been beaten in the first half had Ferran Torres' header hit the target. He made a superb save from the same player in the second half too. Played a key role in the equaliser when he went up for Madrid's corner and won the header.
DF Dani Carvajal, 6 -- In tough away games like this, Carvajal's competitive spirit and non-stop energy are crucial. He saw plenty of action on the right as Madrid looked to break a compact Valencia down, but his final ball was often lacking.
DF Sergio Ramos, 7 -- The captain led the defence in Mestalla's hostile atmosphere, making a number of important tackles and interceptions as Valencia looked to counter attack.
DF Nacho, 7 -- His first start in two-and-a-half months, filling in at left-back in the absence of Marcelo and Mendy. He is more convincing at centre-back but rarely lets the side down.
MF Toni Kroos, 7 -- Kroos has been in good form lately and he got as many touches of the ball as any other player as Madrid dominated possession early on.
MF Fede Valverde, 7 -- His importance to this Real Madrid team grows as the weeks go by. Covers so much ground, gets forward, and combines well with his teammates.
MF Luka Modric, 6 -- Rested last weekend against Espanyol, Modric is no longer a certain starter in Zidane's XI, but for the biggest games the team still feels better with him in it. He was withdrawn to give the team fresh legs for the last 20 minutes.
MF Isco, 6 -- Has cemented his place back in Zidane's side after months out in the cold, but this wasn't his night.
FW Rodrygo, 7 -- Picked ahead of Gareth Bale, the Brazilian teenager did not disappoint initially, frequently switching wings to keep the Valencia defence guessing. Faded in the second half.
FW Karim Benzema, 8 --The key man for Real Madrid, they looked most dangerous whenever the French striker was on the ball. He was in the right place at the right time to score the equaliser.
FW Gareth Bale, 6 -- replaced Isco with 20 minutes to go and struggled to make an impact.
FW Vinicius Junior, 6 -- came on with Bale but didn't see enough of the ball.
FW Luka Jovic, NR -- Had the ball in the net in added time, but the goal was ruled out for offside.