A total of 24 gymnasts are bidding to finish in the top 10 in the Individual competition to qualify for Saturday's final.
They all competed with the ball and the hoop today, with the ribbon and club apparatus rounds tomorrow.
Dmitrieva went to the top of the leader board after two rotations with a total of 57.800 ahead of fellow Russian Evgeniya Kanaeva and Belarus' Liubou Charkashyna.
Kanaeva is the favourite to defend her individual title from Beijing 2008 and become the first two-time Individual All-Around champion in Rhythmic Gymnastics.
Kanaeva, competing with a gold hoop, was marked slightly down after losing control to score 28.100 thanks to a 9.500 difficulty tariff and good artistry.
She then followed up with a spectacular performance with the ball to score a huge 29.525 out of a possible 30 marks to place second with 57.625 ahead of the resumption tomorrow.
Russia (28.375), Italy (28.100) and Belarus (27.900) were leading the way in the Group competition qualifying, with the hoop and ribbon routines to come tomorrow.
The top eight groups will qualify for Sunday's final.