Peter Sagan won one more uphill sprint in the first week of the Tour de France after stage 1 to Seraing and stage 3 to Boulogne-sur-Mer in 2012, stage 2 to Cherbourg in 2016 and stage 3 to Longwy in 2017 as he outsprinted Sonny Colbrelli just like in La Roche-sur-Yon on stage 2. Greg Van Avermaet retained the yellow jersey.
171 riders started stage 5 in Lorient. 2 non-starters: Michael Matthews (Team Sunweb) and Tiesj Benoot (Lotto-Soudal). Robert Kiserlovski (Katusha-Alpecin) crashed out after only three kilometres of actual racing. A 7-man breakaway was formed at km 5: Elie Gesbert (Fortuneo-Samsic), Julien Vermote (Dimension Data), Jasper De Buyst (Lotto-Soudal), Lilian Calmejane and Sylvain Chavanel (Direct Energie), Tom Skujins (Trek-Segafredo) and Nicolas Edet (Cofidis). The BMC team of race leader Greg Van Avermaet was prompt to lead the peloton. A maximum time gap of 4’25’’ was recorded at km 80.