Earlier, a break of nine containing Bram Tankink (LottoNL-Jumbo), Tsgabu Grmay (Trek-Segafredo), Matteo Bono (UAE Team Emirates), Lawson Craddock (EF-Drapac), Oscar Riesebeek (Roompot), Eddie Dunbar (Aqua Blue Sport), Marco Tizza (Nippo-Vini Fantini), Willem Smit (Katusha-Alpecin) and Preben Van Hecke (Sport Vlaanderen-Baloise) held an advantage of over 15 minutes until other teams picked up the pace to bring them back.
Team Sky hit the front of the peloton with Lukasz Wisniowski on the second ascent of the Cauberg in amongst a sea of blue, with Movistar and Astana riders swamping the front of the race.
While the break’s lead was ever dwindling, the Gulpenberg climb saw the pace ramp up with Vasil Kiryienka working hard on the front to place Kwiatkowski as the Polish rider’s rivals for the race win started to circle.
On the Kruisberg, this trend continued, with Quick-Step Floors' Bob Jungels and Tim Wellens (Lotto-Soudal) picking up the pace to eat into the breakaway’s advantage.
The Fromberg saw Ion Izagirre (Bahrain Merida) attempt to bridge to the break, only to see his attack snuffed out relatively quickly before his teammate Enrico Gasparotto reacted fastest to a Roman Kreuziger (Mitchelton-Scott) surge to form a two-man counter.
The third and final time up the Cauberg saw the breakaways join together before Sergio Henao was forced to bring an attack initiated by Greg van Avermaet (BMC Racing) to heel.
However, he was unable to react when the pivotal move came on the Geulhemmerberg, with Alejandro Valverde, Wellens, Peter Sagan, Valgren as well as Jakob Fuglsang and Alaphilippe broke free of Henao and Kwiatkowski.
Despite a concerted effort to bring the leaders back, they were unable to do so and Valgren won by breaking free from that front group in the closing kilometres and out-sprinting Kreuziger.