Olympic champion Christine Ohuruogu slammed her disappointing performance in the 400 metres at the London Grand Prix on Saturday as her nightmare preparation for the World Championships took a turn for the worse. Ohuruogu has been plagued by injuries this year and could only finish third behind Perri Shakes-Drayton and Shana Cox at the World Championship trials in Birmingham last weekend. She fared even worse at Crystal Palace and trailed in last in 51.87 seconds, more than two seconds behind winner Sanya Richards-Ross. It was a jolt to her system with the World Championships in South Korea just around the corner and she said: "I really don't know what happened. I felt really good. I am very, very shocked, that was really appalling." The 27-year-old has not broken 50 seconds since the Olympic final in 2008, while her season's best of 51.49 seconds leaves her outside the top 30 in the world rankings. "I have to be realistic," she added. "I have not done as much training. I am trying to catch up. There's a lot of work to do, a lot to catch up on. It's about what we can realistically do in Daegu. "I have lost a lot of time but I don't want to go to Daegu in a mess. It's a matter of seeing where we can sharpen up in the time we have." Defending world champion Phillips Idowu came third in the triple jump with 17.07m, way behind American winner Christian Taylor (17.68m), but he remains confident of success in Daegu. "To be honest I don't really care," Idowu admitted. "No-one's going to look back in a month's time and say 'I won Crystal Palace.' All I'm focused on now is winning gold in Daegu. "I wasn't expecting massive jumps. I thought I would be able to pull out something which would be good enough to win but like I said last week, I wasn't 100 percent. "I've been working quite hard and all my thoughts have turned to Daegu and I'm in that preparation phase. The work I'm doing in training is not conducive to putting in a great performance out there right now. It's worked for the last two years." Britain's only winner on home soil on the second day of competition came thanks to Lisa Dobriskey in the 1500m. Dobriskey was just 0.01 seconds away from gold at the last world championships in Berlin, but has suffered badly with injuries since then and is due to undergo painkilling injections to ease a back injury shortly. However, the 27-year-old recorded her first victory of the season, holding off team-mate Hannah England to reverse the positions from last week's trials.