NICOLA Sanders didn't just beat her personal best - or even smash it - instead she shattered it into a thousand tiny pieces, smaller than even the smallest Bonsai tree.

After a season plagued by niggling injuries, 400m hope Sanders arrived in Osaka looking distinctly downbeat.

The form that had propelled her to last year's European Championship final and this year's European indoor title had evaporated after a series of knee and Achilles problems.

But she carved more than a second off her previous best as she booked her place in tomorrow's final - breaking the 50-second barrier for the first time in her career.

Her time of 49.77 seconds moves her to third on the all-time British list and ensured she advanced as the second fastest qualifier, behind red-hot Jamaican favourite Novlene Williams.

"What with being injured earlier on in the season it wasn't going great, but I think that's been a blessing in disguise now," said Sanders. "I'm just coming into some form and to run a PB and to get into the final, it's fantastic. But the main event is in two days time. I've just got to get ready for that now.

"It's so open. I mean anything could happen. I'm just glad to be in there in the mix and who knows?"

Sanders will be joined in the final by team-mate Christine Ohuruogu, who also lowered her personal best as she advanced as the fourth quickest qualifier.

But there was disappointment for triple jump medal hope Phillips Idowu, who could only finish sixth in his final.

Idowu had been on course to put himself right in the medal mix until he aggravated a back injury at the UK Championships in Manchester.

He could only manage a best leap of 17.09m - while a repeat of the 17.35m season's best, which won him the Golden League meeting in Oslo, would have been enough for bronze.

Portugal's Nelson Evora produced a national record to take gold with world number one, Brazil's Jadel Gregorio, back in silver.

"I know that if I'm fully fit I can compete but I just couldn't give it 100 per-cent," said Idowu.

"It was an achievement to make the final given my problems. Without the doctors and physios, I wouldn't have been able to jump."

Meanwhile, Kelly Sotherton has lashed out at old team-mates she claims are dragging the sport down with their critical comments.

Former world champions Colin Jackson and Steve Cram have been vocally negative in recent weeks and heptathlon bronze medallist Sotherton is incensed.

"Colin Jackson might say he can't see where the medals are coming from but I can - and I'd tell him if he asked," she said.

"These critics are bringing the sport down in the eyes of the public; some of the team here are really annoyed.

"People are entitled to their opinions, especially when they've achieved at the top level, but they need to try and be positive occasionally.

"We're not out here just chasing pound notes - we've raised our game in the last 12 months and some of us have been treated very harshly.

"The British performances so far have been encouraging. Some people need to stop bothering us, they find it too easy to criticise."

Sotherton also revealed she may quit heptathlon after next year's Olympics to refocus her sights on a bid for a long jump medal in 2012.

World and Olympic heptathlon champion Carolina Kluft has already signalled her intention to do the same and the Birchfield Harrier is relishing a new challenge.

"I think I could be a world class long jumper," she said.

"I want to be able to go to 2012 but I don't want to be injured for the next five years. Unfortunately the life of heptathlete is very injury-prone.

"I get so many niggles already and I just think it would be easier for me to focus on one event and it would keep me motivated.

"I'm not thinking about retiring, just a new challenge. I'll only quit when I stop enjoying it."