[3] The race is seen as one of the cycling Monuments, alongside Milan–San Remo, the Tour of Flanders, Paris–Roubaix and the Giro di Lombardia.

[4] Because Liège–Bastogne–Liège is the oldest of the major races on the cycling calendar, it has the nickname La Doyenne (English: The Old Lady).

[5] In his book The Monuments, Peter Cossins wrote that Liège–Bastogne–Liège "is generally regarded as the toughest one-day race on the calendar".

[9] It was also part of the 2015 UCI World Tour, a season-long competition that included both one-day events and stage races.

Cyclingnews.com described the first change as a "much harder combination" suggested that the new route would make the race more interesting than the 2014 edition, which it described as "painfully dull".

[14] The race began in Liège, in Place Saint-Lambert outside the Prince-Bishops' Palace, with a neutral zone that took the riders out of the town to the south.

The first 75 kilometres (47 miles) of the race brought the peloton south, through Aywaille to La Roche-en-Ardenne; although the roads were not flat there were no difficult or categorised climbs.

The Côte de Stockeu was described by Cycling Weekly as a "killer climb", because of its steep gradient, its narrowness and its poor road surface.

The defending champion, Simon Gerrans (Orica–GreenEDGE) won the 2014 edition in a bunch sprint after a large group came to Ans together.

[20] Alejandro Valverde (Movistar Team) had won La Flèche Wallonne during the week that preceded Liège–Bastogne–Liège and he was one of the major favourites to take the victory.

Valverde's status as the major favourite had the potential to work against him, however, as other riders were expected to mark him closely and perhaps prevent him from winning.

[18][21] Other favourites included Martin, Joaquim Rodríguez (Team Katusha), Rui Costa (Lampre–Merida), as well as Vincenzo Nibali (Astana) and Tim Wellens (Lotto–Soudal).

Gerrans had suffered an injury earlier in the season and had not fully recovered; he was not expected to be able to defend his title.

Similarly, Gilbert had suffered a fall in La Flèche Wallonne; he was also not as well suited to the route of Liège–Bastogne–Liège as he was to the other Ardennes classics.

These were Diego Ulissi (Lampre–Merida), Matteo Montaguti (AG2R La Mondiale), Otto Vergaerde (Topsport Vlaanderen–Baloise), Clément Chevrier (IAM Cycling), Marco Minnaard (Wanty–Groupe Gobert), Anthony Turgis (Cofidis), Cesare Benedetti (Bora–Argon 18) and Rasmus Quaade (Cult Energy Pro Cycling).

It was, however, reduced in numbers, as Quaade, Chevrier and Vergaerde all fell back before the peloton reached the Côte de Wanne, four hours into the race.

[23][24] On the Côte de la Haute-Levée, several riders attacked again to form a smaller breakaway; these were Tanel Kangert and Michele Scarponi (both Astana), Manuele Boaro (Tinkoff–Saxo), Esteban Chaves (Orica–GreenEDGE) and Julián Arredondo (Trek Factory Racing).

They had a 25-second lead at the summit and, although Boaro and Arredondo were dropped on the Col du Rosier, this increased to more than a minute for a short while.

It was reduced to 45 seconds on the Col du Maquisard, however, as the Movistar Team worked hard in the peloton to bring them back.

Among the riders to crash were two previous winners of the race, Dan Martin and Simon Gerrans, as well as Fränk Schleck (Trek Factory Racing), Nicolas Roche (Team Sky), Mathias Frank (IAM Cycling) and Yukiya Arashiro (Team Europcar).

[26] On the Col de la Redoute itself, Kangert was dropped from the breakaway; Scarponi and Chaves had a 35-second lead at the summit and were caught around 10 kilometres (6 mi) later.

[24] The riders then entered the Côte de la Roche-aux-Faucons, where Roman Kreuziger (Tinkoff–Saxo) and Giampaolo Caruso (Team Katusha) attacked; they were quickly joined by Jakob Fuglsang (Astana) and had an 18-second lead at the summit.

[23] Zdeněk Štybar (Etixx–Quick-Step) took over the pace-setting in the peloton as it approached the Côte de Saint-Nicolas and he reduced the gap to Kreuziger, Caruso and Fuglsang.

At the foot of the climb, Daniel Moreno, Caruso's teammate, attacked and built a small gap ahead of the group.

LottoNL–Jumbo had two riders with injuries: Paul Martens broke his hand and Bram Tankink suffered from concussion and bruises.

[30] Dan Martin rode the Tour de Romandie the following week; after he suffered with his breathing through the race, he discovered that he had broken two ribs in the crash in Liège–Bastogne–Liège.

[31] After his strong Ardennes week, Valverde moved into the lead of the UCI World Tour individual rankings, with Richie Porte (Team Sky) dropping to second place.