With the Spaniards 3-0 up from the first leg, they were expected to cruise through the second but found themselves two Mario Mandzukic goals down at the break.
Shortly after the hour mark, they drew level on aggregate as Blaise Matuidi smuggled the ball home after the Costa Rica international had fumbled a routine cross at his feet.
Inevitably, it sparked a rapid reaction from social media, with the keeper coming under fire.
Navas be like pic.twitter.com/l5Go6viVeW— fox (@Fox34345) April 11, 2018
RT if you think Navas is doing a great job in Real Madrid pic.twitter.com/C8F7wmw6PF— SkatanaSaVaal🇿🇦 (@kele_Tebza) April 11, 2018
AHHHHHHHHHHH pic.twitter.com/xH6pOcct3k— Dynamo FC - St Cloud (@DFCSTC) April 11, 2018
Howler by Keylor Navas. But still, if football doesn't work out for him, he has a future playing a sidekick villain in movies. Preferably a drug lord's right hand man. pic.twitter.com/1tvdADp1YU— Paddy Power (@paddypower) April 11, 2018
The incident will inevitably crank up speculation over the future of the No.1, particularly as Madrid have a long-standing interest in David de Gea. Consequently, it was an error that sent shock waves round Manchester.
3-0 to Juventus. Navas huge mistake in goal.— 'Drawty' (@DrawtyDevil) April 11, 2018
United fans right now with De Gea. pic.twitter.com/VuejmSjOgp
United need to get on the phone to Roma for Allison Becker ASAP. No chance Madrid aren't coming in for Dave after that from Navas— Chris Harding (@Chris7Harding) April 11, 2018
United may aswell say bye to De Gea now, Madrid will bid 200M in the summer after that Navas mistake— Jay (@CriticalFirmino) April 11, 2018
I can see why they want De Gea— Isak Pettersson (@IsakIPMusic) April 11, 2018
Let the speculation begin...