It completes another unfortunate season end for Willis, who was injured ahead of the 2009 world championships in Berlin.
His race tactics were in stark contrast to his usual option of easing through the initial laps. He took the lead for the first two but the Kenyan duo of Silas Kiplagat and Asbel Kiprop eventually caught him by the 1000m mark and from there, Willis slipped back steadily through the field. From there Kiplagat, the fastest man this year, and the current Olympic champion Kiprop duelled to the line, Kiprop eventually triumphing in 3m 35.69s. American Matthew Centrowitz took the bronze.
To his credit, Willis has matched the might of East Africa all season, but last night was a race too far. This season, he has been injury free and ran his fastest 1500m time - 3m 31.79s - at Monaco in July. He has backed it up with two other sub-3m 35s times.
All came in the past two months. He was the third-fastest entrant in the field behind Kiplagat (season best time 3m 30.47s), and Kiprop.
The country's medal tally at world championships remains at four field golds (Valerie Adams in the shot put in 2007, 2009 and 2011 and Beatrice Faumuina in the discus in 1997) and one bronze (Adams, 2005).
Meanwhile, Stuart Farquhar finished 11th in the men's javelin final with a best throw of 78.99, well short of his 84.21m season best set at the Diamond League meet in Stockholm. Farquhar qualified for the final with a throw of 82.10m, 1.67m behind top qualifier Guillermo Martinez of Cuba.