Britain's world silver medallist, drawn in lane six, attempted to open up a gap on Watts, running in the fifth lane, but the American, who ran under 44sec at the US trials where he earned the third individual place, had a clear lead going into the finishing straight. Black struggled vainly to keep in contact but was also passed by Alvin Daniel, the Trinidadian winner of last weekend's British trials.
'We are not exactly ecstatic,' Black's coach, Mike Whittingham, said afterwards. He denied the disappointing run had anything to do with the hamstring twinge which has been troubling Black. 'It was just a bad day,' he said.
It was a bad day, too, for Britain's high jump record-holder Dalton Grant, who came last after three failures at the relatively simple height of 2.20 metres.
It was a better day, however, for Tom McKean, who looked as sharp as he has all season in chasing home Mark Everett, the US Olympic trial winner at 800m, and for Sally Gunnell, who pushed another of the US winners from New Orleans, Sandra Farmer-Patrick, close in the 400m hurdles.
Steve Backley, with a javelin throw of 85.90m, and Colin Jackson, with a 110m hurdles of 13.35sec, were Britain's only winners on the night. Black's friend and training partner, Kriss Akabusi, forced by a sore throat to stay at home and miss what he hoped would be his first big 400m hurdles, would have been stretched to keep up with the charge from lane seven of Kevin Young, winner of the US trials, who won in 48.25sec after opening up an early lead which the world champion, Samuel Matete, could not make up.
Elana Meyer's attempt to beat the 5,000m world record of 14min 37.33sec, set in this stadium by Ingrid Kristiansen six years ago, proved unsuccessful, but she was quite satisfied with a runaway victory in 14:51.44 over a field which included Andrea Wallace and Susan Sirma of Kenya.
The South African's time entered the all-time lists as the sixth fastest, and when you consider that three of the times above also belong to her you begin to get a measure of what Liz McColgan will be facing in the 10,000m at Barcelona.
Wallace, who will join McColgan and Jill Hunter as Britain's representatives at that distance, found out at first hand as she finished a distant third in 15:27.04, inside her two-year-old best of 15:47.9 but hardly the stuff to give her the promise of a medal, without which she was loath to consider competing at the Olympic Games.
At the time the pacemaker dropped away, Meyer passed 2,000m in 5:52, just outside world record pace. By 3,000m, at 8:52.67, she was running for nothing more than an ominously impressive victory.
She is delighted with the experience of racing in Europe after the long years of isolation, but she denied that the novelty would cause her to overdo it before the Games. 'I'm only running five races in total before the Olympics,' she said. 'And that was my last 5,000.'
The days when Jonathan Ridgeon could push Colin Jackson over 110m hurdles are long gone, although he is doing all in his power to regain his form of the mid-1980s after missing two years through injuries. Last night, however, the only strong opposition Jackson encountered was the sixth hurdle, which he battered down en route to a relatively sedate victory. Ridgeon finished third in 13.79sec.
Katrin Krabbe, whose escape from a four-year IAAF doping ban has caused concern among German athletics officials, was subjected to a surprise random test before and after training at her Neubrandenburg club yesterday. Grit Breuer and Silke Moeller, the other athletes involved in the controversy, were also tested. The tests, carried out without warning, were made on the orders of the German athletics federation.