Real Madrid made it six wins out of six in the Champions League Group B against Ludogorets and set a Spanish record for consecutive victories.
Already through to the last 16 as group winners, Real, who are the holders, eased to a 19th straight victory in all competitions, surpassing the record of 18 they jointly held with Barcelona.
Carlo Ancelotti’s team came close to scoring several times before the Bulgarian champions were reduced to 10 men after 19 minutes, when the midfielder Marcelinho handled the ball from a corner to keep out a Raphaël Varane header that would have otherwise bulged the back of the net.
Ronaldo slotted his penalty down the middle with a cheeky chip for his 72nd Champions League goal, overtaking the former Real striker Raúl and moving into second behind Lionel Messi, who has 74.
Gareth Bale headed in off the underside of the crossbar at a corner to make it 2-0 in the 38th minute, Álvaro Arbeloa added a third after 80 minutes and the substitute Álvaro Medrán struck the fourth for the dominant home side two minutes from time.
Fired by Ronaldo’s prolific scoring form, Real have won all their games since a 2-1 La Liga defeat at home to Atlético Madrid in September.
They also won all six Champions League group games under José Mourinho in 2011-12, a feat previously achieved by four other clubs – Milan in 1992-93, Paris Saint-Germain in 1994-95, Spartak Moscow in 1995-96 and Barcelona in 2002-03. None of those teams went on to win the Champions League that season. Only Milan, of those teams, reached the final.
Ludogorets had a chance of securing third place and claiming a berth in the Europa League ahead of Liverpool if they had avoided defeat at the Bernabéu.