This was always likely to be the race of the championships and it did not disappoint as Yelena Soboleva bettered her own World indoor record mark** by a monster 0.34 posting 3:57.71.
The imperious Russian, who has set national records for both the 800m and one mile earlier this year, as well as a 1500m World record of 3:58.05** in Moscow last month went into the championships a firm favourite.
And the tall Soboleva proved she could withstand the pressure, reversing the one-two at the 2006 World Indoor Championships with Yuliya Fomenko, who played her part in the world record performance taking silver in a new personal best of 3:59.41.
Behind them, and as a measure of the outstanding quality of the event, Ethiopia's Gelete Burka took bronze in an Area record of 3:59.75 with World outdoor 1500m champion Maryam Jamal of Bahrain also dipping below 4:00 and setting an Area record settle for fourth.
But this was real all about the Russians and Soboleva. The World indoor record holder took an immediate lead and burst through 400m in 1:03.26, tracked closely by her team-mate Fomenko. At 800m, passed in a 2:07.89, the field was already split apart with only the big four in medal contention and Fomenko taking her turn at the front to wind up the pace as the Russians adopted team tactics.
Incredibly, the relentless pace stepped up further in the second half of the race and with two and a half laps remaining the Russians had opened up clear daylight on the Ethiopian-born pair with 1200m reached in 3:11.53.
At the bell Soboleva eased into the lead and simply accelerated away from Fomenko on the final lap. The only real question remained would she smash her own World record? The answer was a resounding, yes. The second 800m was clocked unofficially at 2:05.9, the crowd almost lifting the roof for the history-making achievement.
Behind her Fomenko grimly hung on to silver with Burka, the 2006 World Cross Country short course gold medallist, taking her first global track medal for the bronze.
For Soboleva it capped a remarkable sequence of races this indoor season. She set national records of 1:56.49 for 800m and 4:20.21 for the Mile as well as her World record breaking display of 3:58.05 in Moscow in the National Championships on 10 February.
"I'm really glad about this victory here in Valencia, although I didn't expect to break the world record," Soboleva explained. "Yuliya Fomenko and myself agreed before the race to run at a speed that suited us both and that whoever was strongest would win on the last lap."
Daniela Yordanova also set a Bulgarian record of 4:04.19 for fifth.
Soboleva received a cheque of $50,000 for breaking the world mark. It was the first World record set at the championships since Russia broke the World 4x400m record at the 2004 edition in Budapest.
Steve Landells for the IAAF
**World indoor record subject to ratification
