The result means that both teams remain in mid-table in La Liga, with neither in real danger of relegation.
There were few other chances in the first half until a few minutes from the break when the same two players linked up again. Ebert broke down the right and found Guerra, who made no mistake this time, firing in from the centre of the penalty area.
In the second half the visitors improved, with Jesus Navas getting more involved.
First the winger crossed for Negredo whose header was saved, before the roles were reversed and Negredo released Navas, but his shot from a tight angle on the right was blocked.
Minutes later Valladolid were almost back in front when a quick counter-attack released Ebert on the right, but after beating his marker and then the goalkeeper, the German midfielder saw his shot bounce back off the crossbar.
Negredo then had a chance to get his second but missed the target with just the goalkeeper to beat after collecting Diego Perotti's clever through-ball.
With 10 minutes to go, Guerra then missed a golden opportunity for his second goal, diverting the ball over the bar from three yards out following a drilled cross from the right.
That was the last real chance, as both teams had to settle for a point despite having chances to win the game.