B Dortmund v R Madrid preview

Cristiano Ronaldo is a doubt for Real Madrid's Champions League quarter-final second-leg against Borussia Dortmund after pulling out of Monday's training session with an ongoing knee problem.

Ronaldo completed just 20 minutes of Madrid's final session ahead of Tuesday's clash having missed the 4-0 win at Real Sociedad on Saturday with the injury, which he suffered after scoring Real's third goal in the 3-0 win over Dortmund at the Bernabeu last week.

Manager Carlo Ancelotti said he will delay making a decision, but will not risk the World Player of the Year.

"Cristiano always wants to play and I want him to play, but he is a professional and knows when he can't," he said.

"We have to wait until after training, but we'll take our time with the final decision and we don't want to take any risks."

Dortmund striker Robert Lewandowski insists his side can pull off the seemingly impossible and overturn the 3-0 first-leg deficit.

The Poland striker, who missed the match at the Bernabeu through suspension, is looking for a repeat of his heroics from last season's semi-final when he scored four times in a 4-1 first-leg win over the same opponents.

Not even a repeat of that result would send the Germans into the last four this time, though, and only Deportivo La Coruna have managed to come back from such a deficit in the Champions League, recovering from a 4-1 defeat at AC Milan to win the home leg 4-0 in 2004.

"We need to write history again," Lewandowski said.

"If we can get an early goal, then there's a small chance. We mustn't be afraid.

"We have a minimal chance. It would be crazy to think that I could score four goals again, but we are always dangerous in Dortmund."

Dortmund defender Mats Hummels summed up his side's chances by telling Germany's Kicker magazine they were somewhere in the region of "three percent".

"The most important thing is we try to win and show our fans the passion we have for the game," said coach Jurgen Klopp.

"We've developed a knack of doing well in the second half lately - well this is the second half of the tie."

Madrid are not yet planning for a fourth successive semi-final appearance.

"It's going to be another game, a different game, away to Dortmund," forward Gareth Bale said on the club's website.

"They're obviously going to come out fighting, but we need to treat it the same as any other game.

"Obviously he's (Lewandowski) a great player, he's proven it over the years, but we just have to do out normal job like we did in the home leg and have a good defence."

Madrid will also come up against as intimidating an atmosphere at the Westfalenstadion as Dortmund faced in the first leg.

"There's supposed to be an unbelievable atmosphere," added Bale. "But we're professionals, we know how to handle it and we'll be going out there to try and win as normal."

Dortmund are still without the long-term injury absentees Jakub Blaszczykowski, Neven Subotic, Ilkay Gundogan, Sven Bender and Marcel Schmelzer, while goalkeeper Roman Weidenfeller is a doubt.

Marcelo is likely to miss out again for Madrid due to a hamstring injury.

Watch Dortmund take on Real Madrid live on Sky Sports 2 at 7.45pm on Tuesday.