Ronaldo needs to be fully fit if Madrid want to do the impossible
The Germans are huge favourites to progress to the final at Wembley on May 25 after four goals from Robert Lewandowski handed them a 4-1 win over the Spanish champions in the first leg at Signal Iduna Park last week.
Any hope of a Madrid revival would seem to depend on their talisman Ronaldo fully overcoming a thigh strain he suffered in the first leg.
The Portuguese has scored 50% of Real's 24 goals in the competition so far this season, but missed Saturday's 2-1 win over Atletico in the Madrid derby.
However, he trained on Monday and Real coach Jose Mourinho has confirmed that Ronaldo will play despite continuing to feel his thigh.
Mourinho has called on his side to be more ruthless.
"The team was naive (in the first leg). We played against a player that scored four goals and wasn't fouled in the whole game, whilst Cristiano (Ronaldo) was fouled five times and the game had barely begun. It was like we were playing a friendly," the Portuguese said.
"Mentally and physically we need to be stronger. At the Calderon on Saturday I saw a team that knew how to suffer and defend. A team that was compact, united, aggressive and worked towards an objective."
Mourinho insisted that the outcome of the second leg would not have an effect on his future at the club.
"My future won't depend on that. At practically all clubs, not just Madrid, the success is thanks to the players and the failure is that of the manager.
"We have 90 minutes to play and we are 4-1 down. What I am concerned with is analysing what happened in Dortmund and what we have to do tomorrow (Tuesday).
"The game in Dortmund was so bad that I am not concerned about them, I am concerned about what we have to do better. No player is hiding, we are all in the same boat and all of them want to play, which gives me confidence and hope for the game. In football everything is possible."
Angel di Maria's inclusion in the starting line-up is likely to be the only change in the Real side from the first leg.
The Argentine would have started in Dortmund had the birth of his daughter the day before the game not delayed his arrival in Germany, and he will replace Luka Modric with Mesut Ozil moving back into his preferred central role.
Michael Essien's return to fitness also gives Mourinho the option of playing the Ghanaian at right-back with Sergio Ramos returning to the heart of the defence, but it is expected that the Spanish international will again line up at full-back with Pepe and Raphael Varane being paired in the centre.
Dortmund, meanwhile, have injury concerns of their own with Polish international full-back Lukasz Piszczek struggling with a groin injury he picked up in the first leg.
Midfielders Ilkay Gundogan (neck) and Mario Goetze (hip) are also carrying knocks and manager Jurgen Klopp made 10 changes for Saturday's 2-1 win at Fortuna Dusseldorf.
Klopp insisted his side won't freeze despite their relative inexperience on the big stage.
"I don't think any of our players have played in a Champions League semi-final before, but for us it a similar situation to the German Cup final last year," said Klopp, whose side drew 2-2 in Madrid in the group stage.
"Then we had to face Bayern Munich after we had won the league and they were giving everything, but my players were very cool on that day because the only way to achieve your dream is to be brave so that is what we try to do.
"We could lose the game of course, but the way you lose the game is more important. The players can only give their best and I have no doubt they will do this."
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