Jessica Ennis's joy dashed by officials' error

Jessica Ennis celebrates on the line, but her delight was to be short-lived (PA)

As Jessica Ennis crossed the finish line on the specially constructed sprint strip stretching down Deansgate yesterday, she punched the air in celebration. Six days out from her meeting with her principal Olympic rivals in the Hypo Heptathlon at Götzis in Austria, the Sheffield woman had not only beaten two of the world's leading 100m hurdles specialists – the Olympic champion, Dawn Harper, and World Championship silver medallist, Danielle Carruthers – at their own game but she had done so in a personal best time.

The crowd lining Manchester's main thoroughfare for the Great City Games roared in approval, providing the great British track-and-field hope with a thrilling foretaste of what might come in the London Olympic arena two and a half months from now. The trackside clock flashed up 12.76sec and the winning time was subsequently rounded down to 12.75sec, 0.04sec quicker than Ennis's lifetime best. "I'm really pleased," the beaming European heptathlon champion said. "I didn't expect to run a PB in my first race."

It was only when Kelly Sotherton, the 2004 Olympic heptathlon bronze medallist, hit the Twittersphere several minutes later that it emerged that the personal best was, in fact, invalid. After watching the race on television, Ennis's long-time rival tweeted: "That 100m h was great but I'm sure that there was [sic] only 9 hurdles not 10. Please someone verify!"

Currently recovering from a back problem that forced her out of the Desenzano heptathlon in Italy last month, Sotherton had previous in spotting logistical errors in hurdles races. After running in the 100m hurdles in the London Grand Prix in July 2008, the Birchfield Harrier complained that the third set of hurdles had been positioned in the wrong place and her protest was upheld. She was right again yesterday. Scrutiny of television replays showed that the athletes had negotiated just nine flights, not the requisite 10.

All of which rendered the result invalid and took the shine off Ennis's sunny mood. "That is so, so annoying," she said, when the confirmation of the cock-up came through. "I just feel like it's such a wasted race now. I was obviously running well at the end. Stick another hurdle on and it would have been the same outcome. But I'm so annoyed.

"I'm going to walk down the track next weekend in Götzis and check the hurdles. I can't believe it. It's a great event here but that is a massive, massive mess-up. There should be no mistakes like that."

Indeed not. "It's a very unfortunate mistake," David Hart, communications director for event organisers Nova International, said. "We would like to apologise for this unacceptable incident, and in particular to the athletes."

Sotherton was somewhat contrite too. "I feel bad!" she tweeted. "People probably think I'm being a cow bag."

Dwain Chambers was also concerned about public reaction yesterday but, in his first race on home soil since the lifting of the British Olympic Association ban on the selection of reinstated doping offenders, the Belgrave Harrier received a rousing reception. The 150m race distance was a little too long for the 100m specialist, who finished runner-up to American Wallace Spearmon in 15.27sec, but Chambers was a happy man afterwards. "It was great to get a reception like that," he said. "I was unsure what it was going to be like."