The harshness of August in Beijing is old hat for Stephanie Twell, the 18-year-old whose place on the plane to the Olympic Games should be confirmed when the final names in the Great Britain team are announced tomorrow. Twell, who became world junior champion in the 1,500 metres in Poland last week, ran a personal best time at the Golden League meeting here last night. Twell is a name to look for in London in 2012, but the experience she gains next month could prove invaluable.

Two years ago, Twell ran in the World Junior Championships in Beijing. She finished twelfth, but experienced a training camp in Macau - where Britain’s athletes will acclimatise for the Olympics – and the humid, polluted conditions that many athletes are afraid of in the Chinese capital. “We were the guinea pigs,” Twell said. “The conditions were fine. Our bodies were so stressed by the heat and humidity in Macau that when you come to Beijing it feels a lot cooler. Winning the world junior title has definitely given me more confidence. I ran Golden League before and lined up next to the world champ [Maryam Yusuf Jamal] and I was in awe of what she had achieved. Now I think, ‘they’re here to race me, I’m not just here to race you’ .”

Twell, who will be 19 two days before the 1,500 metres heats in Beijing, recorded 4min 05.83sec, finishing eighth behind Jamal’s winning time of 3min 59.99sec. “I was working in lane two for quite a time,” Twell said. “I think I can go faster.”

Jenny Meadows, who missed last week’s Olympic trials with a chest infection, effectively guaranteed her place in the 800 metres in Beijing by running a personal best of 1min 59.11sec, finishing sixth behind Pamela Jelimo, the Kenyan, who broke her own world junior record with 1min 54.97sec. “I hadn’t raced for four weeks and I don’t quite feel myself, so I’m delighted,” Meadows said. “I really feel if I was fit I could have come second.” She runs in the Aviva London Grand Prix at Crystal Palace on Friday. “And Beijing . . . hopefully,” she added. Jelimo stayed on course to share the $1 million (about £500,000) bonus for winning at all six Golden League meetings, with Blanka Vlasic, of Croatia, who won the high jump.

Andrew Lemoncello also ran a personal best of 8min 22.95sec in the 3,000 metres steeplechase to virtually guarantee Olympic qualification.

Jeremy Wariner, the world and Olympic 400 metres champion, proved a point to LaShawn Merritt, who beat him in the US trials, by winning the 400 metres in 43.86sec, the fastest time in the world this year and 0.49sec ahead of Merritt.

However, Merritt was upset after being denied the lane he was promised and found Wariner on his inside. “All I’m saying is this sport is messed up,” he said. “But I’m not going to throw excuses out there. I ran and I feel good.”