Real Madrid set a new Spanish record of 19 successive wins as they advanced to the Champions League last 16 with a routine 4-0 victory over Ludogorets.

Cristiano Ronaldo converted a penalty to register his 72nd Champions League goal, before Gareth Bale climbed to head the holders' second.

Defender Alvaro Arbeloa's shot crept in for the third, before substitute Alvaro Medran completed the scoring.

Medran replaced Bale after the Welshman suffered a bloodied nose.

Bale came off injured in the 82nd minute

Bale sustained the injury in a collision with defender Georgi Terziev as he burst into the penalty area, but it looks unlikely to keep him sidelined for any significant time.

Real's unbeaten run stretches back to the 5-1 victory over Basel in their opening Champions League Group C game on 16 September and surpasses the 18-game mark set by Barcelona in 2005-06 season.

Carlo Ancelotti's side's early season form had been patchy with three defeats in their opening five games.

Their current streak never looked likely to come to an end against Ludogorets, who had defender Marcelinho sent off in for a deliberate handball that led to Ronaldo's penalty.

The Bulgarians were penned back for much of the match, and could have conceded more from Real's 13 shots on target but for goalkeeper Vladislav Stoyanov's solid performance.

Real Madrid, whose perfect record of six wins from six Group C games ensures them a draw against one of the other group's runners-up in the knockout stages, play Almeria on Friday, before setting off for the Club World Cup in Morocco.