Kelly Sotherton won Britain's first medal of the World Championships when she took bronze in the heptathlon.
Sotherton put in a season's best performance to finish third
A poor javelin saw Sotherton drop back to fourth but she overhauled Austra Skujyte after a battling 800m, finishing with 6,510 points.
Fellow Briton Jessica Ennis finished fourth overall, 41 points behind.
Carolina Kluft of Sweden, who broke the European record with 7,032, claimed a third consecutive world crown ahead of Lyudmila Blonska of the Ukraine.
Sotherton said: "I wanted the medal so much, especially after such a poor start to the year, and put in a lot of hard graft.
"After six events I thought, here we go again, but fortunately I had one event left. The only person I was going to lose to [in the 800m] was Jess. I was pushed all the way by her.
"She's not far off taking Kluft's mantle in the next few years. She's the future, so everyone had better watch out."
Ennis, 21, said: "This is my first Worlds and to come fourth is fantastic. It's amazing to compete in front of this crowd. I can't imagine what it's like to win a medal but I want to be there in future.
"I'm still regretting the shot putt. If I had thrown near to my personal best then it would have put me in a mix for a medal but it's the way it happens."
Sotherton lay in third place overnight and cemented her position with a personal best leap of 6.68m in the long jump.
Ennis managed 6.33m - seven centimetres short of her PB - but it was good enough to stay fourth and in contention.
In the penultimate event, the javelin, Sotherton thew a season's best 31.90m but her inability to conquer her Achilles heel saw her slide back to fourth, with Ennis, who landed a personal best 38.07m, behind in fifth.
The British duo worked together in the closing 800m.
Sotherton had to beat Austra Skujyte by nearly three seconds to snatch the bronze and at the bell she was well ahead as the Lithuanian struggled at the back.
But the Olympic bronze medallist started to slip backwards on the back straight and Ennis went to the front to drag her along.
Ennis won the 800m in two minutes 11.39 seconds just ahead of Sotherton while Skujyte trailed home last.
Kluft celebrates after winning a third world title with a personal best
Kluft remained imperious as the best all-round female athlete - she has not been beaten since 2002 - with another superlative display in Japan.
The 24-year-old Swede set the second best points total of all-time behind Jackie Joyner-Kersee's world record of 7,291.
"I broke my personal best and I feel so good," Kluft said. "It's been a big pressure on me and I vowed to keep it all together, and now I have my third world title."
Christine Ohuruogu's comeback from a one-year ban gathered pace on day two in Osaka as she eased into the 400m semi-finals.
Commonwealth champion Ohuruogu clocked a season's best 50.46 seconds.
Ohuruogu, who has only just returned after being suspended for missing three out-of-competition drugs tests, won a warm-up race last week and became the fastest Briton over 400m this season.
But the Londoner surpassed that time during qualification and another controlled performance suggests that she is closing in on her personal best of 50.28.
Ohuruogu is joined in Monday's semis by Nicola Sanders and Scot Lee McConnell.
Sanders finished a strong second to US champion DeeDee Trotter in a time of 51.45 with Ireland's Joanne Cuddihy third in 51.55.
"It was pretty tough out there in the heat," Sanders, the European indoor champion, said.
"I am really confident. I had psyched myself to think it was going to be really hard but it was much, much better so hopefully that bodes even better for the semis and Wednesday's final."
I have never experienced anything like that before in my life
McConnell set a season's best of 51.44 to go through and said: "I had some fight in me in case I needed to got a little quicker."
Laura Turner advanced to Monday's 100m semi-finals, finishing fourth in her heat behind the experienced Veronica Campbell and Kim Gevaert in 11.32 seconds.
Turner, 25, said: "I'm in the semi-finals but the time was rubbish. I'll be fresher on Tuesday and will get the adrenalin going."
Team-mates Montell Douglas and Jeanette Kwayke both failed to advance.
No British women qualified for the 800m final, although Marilyn Okoro, who came fourth in her heat in a time of 1:59.63, and Jenny Meadows, who finished fifth in her heat with 1:59.39, posted personal bests.
Jemma Simpson was sixth in her heat in a time of 2:00.48.
"It was very quick, I knew it would be, but I wasn't close enough to the front to give myself a chance," said Okoro.
"I wanted to go off hard and hold my position. I've learned that you have to run sub two minutes to go through each round - you have to be stronger."
Meadows said: "I was really surprised as the pace was rapid at the start so I'm delighted to run that time."
There was disappointment for Scot Andrew Lemoncello, who failed to advance to the final of the men's 3,000m steeplechase.
The 24-year-old, who had suffered a bout of sickness at the holding camp in Macau, finished last in his heat and more than 30 seconds off the required qualifying standard.
"I don't know what happened, there was nothing left in my body, I have never experienced anything like that before in my life," said Lemoncello.
"I just don't know what I did wrong. It was just a horrible, horrible experience."
Kate Dennison failed to qualify for the women's pole vault final as she only managed to clear 4.20m.