(CNN) -- Swimming legend Michael Phelps struggled in his attempt to adapt to the old-style racing suits at the World Cup short-course event in Sweden on Tuesday.
The 14-time Olympic gold medal winner qualified for finals in only one of three events in Stockholm, his best result being seventh of eight to go through in the men's 100 meter medley.
Racing for the first time since winning five golds and a silver at the world championships in July, the American missed out on the 100m freestyle after qualifying in 16th of 23 competitors.
His time of 47.77 seconds was 1.84 seconds slower than the leading mark set by Sweden's Stefan Nystrand.
The 24-year-old, who was disqualified in the 100m backstroke, set a time of 53.13 seconds in the medley. The fastest man, South African Darian Townsend, came home in 52.48.
Phelps was one of the few swimmers to revert to the old-style suits, which will become mandatory after January 1 as world ruling body FINA seeks to rein in the high-tech costumes which have sent records tumbling at an incredible rate in the past two years.
He will swim in the 100m butterfly and 200m medley heats on Wednesday, and then head to the next leg of the World Cup in Berlin at the weekend.
In Stockholm on Tuesday, Chinese swimmer Jing Zhao set a new world record in the heats of the women's 50m backstroke, clocking 26.08 seconds.
She beat the mark of 26.17 posted by Australia's Marieke Guehrer in the previous meet of the series in Moscow on November 6.
In the men's 50m butterfly, South Africa's Roland Schoeman was first in a new World Cup record of 22.29.