Off the back of numerous attacks on the slopes of the Roche-aux-Fachons, it was Jungels who made the most of opportunity, surging clear and then displaying his time-trialling prowess to solo clear to the finish.
The early break was composed of Florian Vachon (Fortuneo-Samsic), Jérôme Baugnies (Wanty-Groupe Gobert), Loïc Vliegen (BMC), Anthony Perez (Cofidis), Mark Christian, Casper Pedersen (both Aqua Blue Sport), Paul Ourselin (Direct Énergie), Antoine Warnier (WB Aqua Protect Veranclassic) and Mathias Van Gompel (Sport Vlaanderen-Baloise).
The break got out to a maximum advantage of six minutes and ten seconds to the chasing peloton, but the relentless chase of Rory Sutherland (UAE Team Emirates) and Winner Anacona (Movistar) saw the gap being gradually reduced.
The arduous pace also meant that the peloton began to lose riders at a steady rate, dropping off the back as the 2018 edition of Liege-Bastogne-Liege devolved into a race of attrition behind.
There were few tactical moves with most major teams looking to keep their powder dry until the major climbs in the final 30 kilometres of the race.
The breakaway wasn't experiencing much cohesion, with attacks from Pedersen and Baugnies reducing the cooperation of the riders up front. The Baugnies attack proved to be the strongest, with the Wanty-Groupe Gobert rider the final one to be caught with 22 kilometres to go.
From there, it was a frantic dash into the foot of the Roche-aux-Fachons, the steep climb expected to be significant to the outcome of the race.
A series of attacks opened up the race, with Phillipe Gilbert (QuickStep Floors) and Sergio Henao (Team Sky) trying to get away on the early slopes. While those moves were kept under control, it paved the way for Jungels to jump clear further up the ascent.
The 25-year-old quickly established a handy gap, keeping it over the summit of the Roche-aux-Fachons, before diving down the sharp descent.
There was a mix of hard-riding by Jungels and messing around in the elite chasing group behind, with attacks from Dan Martin (UAE Team Emirates) and Alejandro Valverde (Movistar), as well as a general lack of cooperation, causing the momentum to stall.
Jungels was able to push out his advantage to 51 seconds at the foot of the final climb, the Cote de Saint-Nicolas. Jelle Vanendert (Lotto Soudal) put in a massive attack from the chasing group, distancing himself from the pack and cutting the escaped Jungels gap in half by the top of the climb.
The rest of the chasing group stayed together, with an unfortunate puncture for Martin the highest profile casualty. Many attacks tried to go clear to chase down the escapees, but Romain Bardet (AG2R La Mondiale) and Michael Woods (EF Education First-Cannondale) were the only ones to get away to try and track down the riders ahead of them on the road.
Coming to the rise to the finish line within the final kilometre, it was clear that Jungels had done enough to hold off a flagging Vanendert, and he took his time to celebrate as he crossed the line.
Behind him, Vanendert exploded on the final section of the last hill and was passed by the two chasers and the group, with Woods outsprinting Bardet for second place.