LISBON -- Gareth Bale is facing a battle to be fit for Real Madrid's Clasico clash with Barcelona after being injured during Tuesday's 2-1 Champions League victory against Sporting Lisbon in Portugal.
Wales forward Bale limped out of the Group F tie on 58 minutes after appearing to injure his right ankle following a challenge with Sporting defender Sebastian Coates.
The former Tottenham Hotspur player had attempted to continue in the game after receiving lengthy treatment on the sidelines, but lasted less than a minute after returning to the action before signalling his inability to continue.
Real, currently four points clear of Barcelona in La Liga, face Luis Enrique's team at the Camp Nou on Dec. 3 in the first meeting between the two clubs this season, but coach Zinedine Zidane admitted Bale must undergo tests on Wednesday before he can predict whether he will be fit for the trip to Catalonia.
"Bale suffered an injury, but he needs a thorough examination tomorrow to see the extent of it," Zidane said. "It is too soon to say how long he will be out for or the size of the problem.
"We will see, so I don't know yet if he will be for the Clasico."
A draw on Tuesday night would have been enough to send Los Blancos through to the Champions League knockout stage alongside Dortmund, who romped to a record 8-4 win over Legia Warsaw and will now come to Madrid next month in a showdown for top spot.
It appeared Zidane's side would be left with just that after a penalty from Adrien Silva after 81 minutes had cancelled out Raphael Varane's first-half opener, with the home side having seen defender Joao Pereira sent off after appearing to punch Mateo Kovacic.
However, with just three minutes left, Benzema nodded in a weighted cross from Sergio Ramos to secure victory as Real extended their unbeaten run to 30 games in all competitions.
Zidane, who had made just one change to the side which beat city rivals Atletico 3-0 at the weekend, was pleased with the way the team went about their job in Portugal.
"We had our difficult moments in the game but that is normal,'' he said. "In the previous game against us Sporting played with the same intensity and they didn't drop their heads after going behind. But we managed to score a wonderful second goal through Karim Benzema.
`"It was important that we won here; we achieved what we came to get. We are going to play a final against Dortmund now."
Next up for Real is a home match against Sporting Gijon and then the second leg of their Copa del Rey tie against Segunda Division B side Cultural Leonesa, which they lead 7-1.
"What we want to do is to continue working hard in order to achieve our objectives," Zidane said. "We must look to recover because it isn't easy for these players playing every three days.''
Sporting, meanwhile, must now focus on getting the required result from their final Group F tie away to Legia Warsaw to secure third spot and progression to the Europa League.
Coach Jorge Jesus said: "The difference between the two sides was only in the final result. In the game Sporting was equal to Real Madrid, tonight the red card for Joao Pereira was decisive.
"We were great both technically and tactically. We only missed a few details. My players did well and, with time, they will learn not to fail in those small details.''
Information from Press Association Sport was used in this report.