Usain Bolt is expected to consolidate his position as world No.1 Sprinter
The first track and field medals go up for grabs at the Olympics here Friday as American swimming superstar Michael Phelps chases his third gold of the Games.
With swimming due to complete its programme on Saturday, the transition to athletics begins at the 80,000-capacity Olympic Stadium with the women's 10,000m and men's shot put to be decided.
British athletics' golden girl Jessica Ennis will also make her entrance as the opening rounds of the heptathlon get under way, while Welsh 400m hurdles world champion Dai Greene also begins his preliminary rounds.
Former world champion Ennis, who most recently won silver medals in the 2011 worlds in Daegu, and world indoor pentathlon in Turkey in March, missed the Beijing Olympics through injury is under pressure to perform.
Up against Ennis will be Russian world champion Tatyana Chernova and Ukraine's Natalia Dobrynska, who won the 2012 world indoor pentathlon title just days before her husband and coach, Dmytro Polyakov died.
The women's 10,000m has been built up as a duel between Kenya's world champion Vivian Cheruiyot and Ethiopia's defending Olympic champion Tirunesh Dibaba, with both eyeing a middle-distance double.
Dibaba has been wracked by injuries since her double gold medal-winning performances in Beijing, and will be bidding to emulate her cousin Derartu Tulu by winning two Olympic gold medals in the women's 10,000m.
Cheruiyot comes to London in great form, however, and will seek to carry on her imperious form from last summer's Daegu worlds when she won the 5000-10,000m double.
The shot put sees 22-year-old world and European champion David Storl of Germany taking on a strong US trio of throwers led by Reese Hoffa.
At the Aquatics Centre, Phelps will aim to consolidate his position as the most decorated Olympic athlete of all time in the 100m butterfly.
Phelps roared back to form on Thursday with an imperious victory in the 200m individual medley, consolidating his newly acquired status as the most successful athlete in Olympic history with a record 20th medal.