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By Tim Hanlon
May 7 (Reuters) - Real Madrid's La Liga title challenge was left hanging by a thread after a late Humberto Osorio header earned Real Valladolid a 1-1 draw and Cristiano Ronaldo suffered an injury on Wednesday.
Real, hoping to keep the pressure on Atletico Madrid at the top of table, remained in third place, four points behind their city rivals and a point adrift of Barcelona with two games to play.
"It is practically gone now but while there is a mathematical chance then Madrid are obliged to keep going. It has been a long season and it takes its toll on the body," Real defender Sergio Ramos told reporters.
The match started badly for Real when world player of the year Ronaldo hobbled off with a suspected hamstring strain.
They went ahead, however, when Ramos, celebrating the birth of son Sergio on Tuesday and his 400th Real appearance, swept home a free kick after 35 minutes.
It was not enough, though, as relegation-threatened Valladolid levelled when Osorio nodded home with five minutes left.
"We wasted a unique opportunity and we will now have to examine it calmly. With 10 minutes to go we relaxed and against a side battling for survival they are always going to make it difficult for you," added Ramos.
The result opened the door for Barcelona, who know that a win in the final match of the season against Atletico would hand them the title providing they beat Elche away on Sunday.
Real, who play Atletico in the Champions League final this month, were missing the injured Gareth Bale and Angel Di Maria played in as three-pronged forward line as Luka Modric returned in midfield.
Valladolid set out to counter-attack using the pace and movement of Jeffren and Zakara Bergdich on the wings, and they caused problems for the Real defence with a Javi Guerra header going close in the opening minutes.
Ronaldo's injury seemed to affect the spirit of the Real players as they were too static and predictable in possession.
Valladolid sensed the chance of an upset and linked up well again in attack with Oscar Gonzalez firing over inside the area.
However, Ramos, who had earlier gone close with a header, was on hand to steady Real's nerves with the opening goal, his fifth in the last four games.
As Real sat back after the break it invited Valladolid to come back at them and they got a deserved equaliser through Osorio. (Editing by Ed Osmond)