Johnson, who retained his individual 400m title on Tuesday, has pulled out with a leg injury. It never does to underestimate the strength in depth of American 400m running, the news will hve done nothing but good for the morale of the British squad.
After the disappointment of missing a medal despite having three men in the individual final, there will now be rising hopes that Iwan Thomas, Mark Richardson, Jamie Baulch and the incoming British team captain, Roger Black, can make a serious impact on the final day of the championships tomorrow.
Wilson Kipketer made his expected impact on the 800m field in yesterday's final, but although he earned his $60,000 (pounds 37,000) first prize, there was no world record bonus of $100,000 for him as he finished in 1min 43.38sec, well outside Seb Coe's 16-year-old mark of 1min 41.73.
As Haile Gebrselassie pointed out more than once before retaining his 10,000m title the other night, this is a hard, sprinter's track. Kipketer, who equalled Coe's mark last month, is likely to surpass it in Zurich next Wednesday.
Kipketer, whose thin legs generate almost unearthly speed, took the lead as the runners broke from their lanes and kept it without apparent difficulty.
Norberto Tellez completed a good evening for Cuba by taking the silver in 1:44.00.
The victory was sweet in itself for Kipketer, who was not allowed to run in the Olympics because the IOC were not satisfied he had established full citizenship in Denmark after moving from his native Kenya. When he refused to run for Kenya in Atlanta, his former president, Daniel Arap Moi, described him as a traitor. Last night, Kipketer was proud to fly the flag for Denmark.
Earlier in the day came confirmation that Richard Nerurkar had been forced to pull out of tomorrow's marathon because of a viral infection picked up in the last few days.
It was a wretched turn of events for a competitor whose meticulous preparations have earned him a consistently good championship record. Fifth in last year's Olympics, seventh in the last worlds, and fourth in the Europeans, he had also shown the ability to run in hot and humid conditions.
More encouragingly, Nick Buckfield cleared 5.70m, one centimetre below his record, to qualify for tomorrow's pole vault final.