Gareth Warburton withdrew from going head-to-head with Welsh rival Joe Thomas at the Swansea International to boost his World Championship bid.
The 28-year-old felt Wednesday's meet would not help his quest to qualify for South Korea because it was a 600m race, won by Cardiff's Joe Maynard.
Warburton ran a season's best 1:46.95 to finish third in the 800m at the European Team Championships on Sunday.
But he is still one second off the qualifying time for his first Worlds.
Michael Rimmer has taken one of Team GB's two 800m spots at Daegu and Warburton must hit the 1:45.40 mark.
Warburton wants to join fellow Welsh athletes Dai Greene and Christian Malcolm at the 13th World Championships, which start on 27 August.
Commonwealth and European 400m hurdle champion Greene and 200m sprinter Malcolm have already achieved the UK Athletics 'A' standard.
Rhys Williams, 400m hurdle silver medallist at the 2010 Europeans in Barcelona, and discus thrower Brett Morse have achieved the lower 'B' standard.
Welsh pole vaulter Sally Peake and Warburton, who finished fourth at the 2010 Commonwealth Games, are close to qualifying.
And the 800m runner, second fastest Brit behind Rimmer this year, hopes some top-level competition will inspire him to dip below the qualifying standard before the team is announced on 8 August.
Peake has jumped 4.20m and requires another 20 centimetres to make Team GB's lower qualifying standard.
Morse, who won the Swansea International discus title by almost 10m, is British number one and virtually certain to make his World Championship debut.