Ronaldo scored his 100th Champions League goal for title-holders Real from the penalty spot late in the first half yesterday to cancel out Adrien Rabiots opener for the French side at the Santiago Bernabeu, set up by Neymar.
The Portuguese star then turned the ball home from close range with seven minutes left before Marcelo secured what could turn out to be a decisive first-leg lead ahead of the return in Paris on March 6 and sent nearly 80,000 home fans into raptures.
"We need to keep playing like that, with the desire to defend the Champions League. You can never consider Real Madrid to be dead and buried."
Rabiot said PSG were plagued by familiar problems.
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"We always say the same things and we always get caught out in the same way," Rabiot told beIN Sports.
"The problem is its easy to score eight against Dijon, or four goals in league games. It is in these matches that you need to be decisive." "
Neymar, in Barcelonas ranks then, could not make the difference for PSG, who now have a huge job on their hands to turn the tie around.
Having looked set to come away with a precious draw, the defeat piles the pressure on coach Unai Emery, but for Real the outcome is an enormous boost for their boss Zinedine Zidane.
Under pressure himself with Real flagging domestically, he needed this win, and will earn praise for his substitutions, with Marco Asensio coming off the bench to set up each of the two late goals.
Emery went even further, dropping his captain Thiago Silva to make way for 22-year-old Presnel Kimpembe in the centre of the PSG defence.
- Difficult night for Neymar -
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Real supporters chose an image of a famous fan in Rafael Nadal to adorn a display unfurled at the south end of the ground as the sides came out, hoping their team could draw inspiration from someone who has conquered Paris 10 times as French Open champion.
Ronaldo, meanwhile, saw Alphonse Areola make a fine save from his net-bound shot after he had been released by Marcelo, and not long after that, in the 33rd minute, PSG scored.
Neymar could claim an assist, although it didnt look like the Brazilian meant to help Kylian Mbappes low ball across the box from the right into the path of Rabiot, who swept home unmarked.
Areola, having just made a superb save from Karim Benzema, could do nothing to keep out Ronaldos spot-kick.
The visitors had chances to go ahead again in the second half, Keylor Navas saving well from Mbappe and Sergio Ramos blocking bravely from Rabiot.
Emery then surprisingly took off Edinson Cavani and replaced him with Thomas Meunier, a right-back. But it was Zidanes decision to send on Asensio that proved crucial.