Former European 400m hurdles champion Rhys Williams finished a disappointing sixth in his heat at the Atletica Geneva meeting in Switzerland.
But his time of 51.24 seconds was an improvement on the 53.45 sec he ran in winning at the Welsh Athletics Regional Championships in Newport in May.
That had been the Welshman's first race since serving a ban for failing a drugs test in July 2014.
David Omoregie won the 110m hurdles B final in Geneva in 13.76 sec.
Williams has set his sights on a place in the Great Britain team for August's World Championships in Beijing, but would have to finish in the top two in the British Championships on 5 July to be selected and also needs to meet the qualifying time of 49.50 sec at an event before Beijing.
The 31-year-old was leading a 12-strong Welsh contingent at the Swiss event.
Paul Walker claimed a creditable joint second in the pole vault with 5.20 metres, while sprinter Dewi Hammond qualified for the 100m A final but finished seventh in 10.52 sec - 0.17 behind winner and fellow Briton Roy Ejiakuekwu.
Women's 400m runner Laura Maddox ran 53.59 to top her heat and record the 10th fastest time in the event.
Sprinters Mica Moore and Elaine O'Neill both failed to qualify from their heats in the 100m, and along with Hannah Thomas were also off the pace in the 200m.
Emily Wright was fifth in the long jump with a distance of 5.92m
Meanwhile, four Welsh athletes have been selected to represent Great Britain & Northern Ireland at the European Team Championships in Russia this month.
Brett Morse (discus), Sally Peake (pole vault), Laura Maddox (4 x 400m relay) and Rhianwedd Price (1500m) will be part of a 47-strong GB and Northern Ireland team competing in Cheboksary on 20 and 21 June.
At the 2014 European Team Championships in Braunschweig, GB & NI finished fifth overall with a total points score of 281.5.