London - South African athlete Caster Semenya made a solid start to her Olympic Games campaign when she ran to qualify for the semi-final of the women's 800 metres in London on Wednesday.

The favourites in the two-lap race revealed little of what could be expected of them ahead of Thursday's semi-final, as they did just enough to advance to the next round.

Semenya crossed the line in second place with a time of two minutes, 00.71 seconds (2:00.71).

The United States' Alysia Johnson Montano went out fast and led from start to finish, clocking a time of 2:00.47.

Semenya ran a more calculated race, as she held back over the first lap with Montano opening a gap between her and the rest of the field.

Towards the final stage of the race, it seemed as if Semenya had left her famous kick too late as she was lying in third, but she surged in the final 100m, almost pipping Montano to the finish.

The 20-year-old said she was satisfied with her race, but said little about her tactics in the fastest race of the six heats.

"The race seems to be okay, it was a little bit faster from the first lap, I just had to maintain the pace to finish in the top three," Semenya said.

"It is very important -- 800m is a tactical race -- you have to know how to run from back to front... that is the way to run 800m.

"For you to be a good contender, you have to run under two minutes, so that is what I am looking for."

Most of the medal contenders progressed to the semi-finals, with Ethiopia's Fantu Magisu the only big gun not to compete. She pulled out before the race due to injury.

Olympic champion Pamelo Jelimo, from Kenya, recorded the second fastest time of the heats, clocking 2:00.54.

World champion Mariya Savinova, of Russia, also reached the next round with a time of 2:01.56.

The South African's best time this season is a pedestrian 1:59.18, which is only the 21st fastest in the world this year.