America's 4x100m team clinched world championship gold after anchorman JJ Johnson pipped Britain's Dwain Chambers on the line.
Chambers was out in front after the last baton change but was overhauled by Johnson, who belied his status as the weakest link in the US team.
The 26-year-old Chambers, who was fourth in the individual 100m, said he was delighted to have captured a medal, but his disappointment at not hanging on to take gold was evident.
"It is great to have taken the team baton round and made it onto the medal rostrum, " he said.
"But when you are ahead, you have got to stay ahead - though it is easier to chase."
Britain's quartet of Christian Malcolm, Darren Campbell, Marlon Devonish and Chambers clocked a season's best of 38.08 seconds, two hundredths behind the US.
The race developed as expected as the US and Britain - the two fastest qualifiers - led the rest of the field from the start.
And it remained fiercely competitive until the very last when Johnson achieved the unlikely by chasing down Chambers to bring the US another sprint victory.
1. USA (J Capel, B Williams, D Patton, J Johnson) 38.06secs
2. Great Britain (C Malcolm, D Campbell, M Devonish, D Chambers) 38.08
3. Brazil (V de Lima, Ribeiro, A da Silva, C Souza) 38.26
4. Netherlands (T Beck, T Douglas, P van Balkom, C Douglas) 38.87
5. Nigeria (A Fasuba, U Emedolu, D Musa, D Aliu) 38.89
6. Poland (P Balcerzak, L Chyla, M Nowak, M Urbas) 38.96
7. Japan (H Tsuchie, H Miyazaki, R Matsuda, N Asahara) 39.05
DNF Jamaica (R Williams, D Thomas, M Frater, A Powell)
MMIX
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