British medal hope Tiffany Porter is safely through to the semi-finals of the 100m hurdles after finishing third in her Olympic opener.
(4:07.29) made it through to the 1500m semi-finals.
was Britain's sole 800m qualifier as
Lawrence Okoye qualifies in fourth place for the Olympic final
reached Tuesday's discus final, with 65.28m in his final throw.
There was no place for promising thrower
who only recorded 58.18m and 60.08m.
Osagie finished strongly in 1:46.42 to just edge third place in his heat and secure a spot in the 800m semi-finals, but Warburton and Rimmer, who was expected to qualify, could only manage fifth-place finishes.
Porter raced to a time of 12.79 seconds behind heptathlete Jessica Zelinka of Canada (12.75) and Bulgaria's Alina Talay (12.71).
There were doubts about Porter's fitness after she finished last at the London Diamond League last month and
appeared to be injured.
Australian world champion and world number one Sally Pearson is also through to the semi-finals after dominating her heat, winning in 12.57.
Olympic heptathlon champion Jessica Ennis has decided not run in the 100m hurdles, despite setting a personal-best time of 12.54 on Saturday.