Football: Real's Ronaldo breaks off training in Dortmund due to knee injury

Real Madrid's Cristiano Ronaldo at the training session in Dortmund on April 7, 2014, which he only completed 20 minutes of. -- PHOTO: REUTERS
Real Madrid's Cristiano Ronaldo at the training session in Dortmund on April 7, 2014, which he only completed 20 minutes of. -- PHOTO: REUTERS

DORTMUND (AFP) - Cristiano Ronaldo is doubtful for Real Madrid's Champions League quarter-final, second-leg against Borussia Dortmund after breaking off Monday's final training session with a knee injury.

Ronaldo completed just 20 minutes of Real's final training session on the eve of Tuesday's match at Dortmund's Westfalenstadion having sat out Real's 4-0 win at Real Sociedad on Saturday to recover from the problem.

The 29-year-old suffered the knee injury after scoring Real's final goal in their 3-0 win over Dortmund at Madrid's Bernabeu Stadium last Wednesday and sought treatment in Dortmund immediately after breaking off training.

Madrid's Italian manager Carlo Ancelotti has said he will delay making a decision on Ronaldo and 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," said Ancelotti before overseeing the final training session.

"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."

Portugal star Ronaldo is Real's top-scorer this season having hit the net 45 times in all competitions.