Michael Phelps admitted he has work to do after finishing second in the 100 metres freestyle at the Charlotte UltraSwim last night, 24 hours after losing his first final in nearly a year.

The American, who won a record-breaking eight golds at the Beijing Olympics last summer, finished nearly a full second behind France's Frederick Bousquet.

The three-day meeting in North Carolina was Phelps' first competition since the Games, a return which had been delayed by a three-month ban after he was photographed appearing to use a pipe associated with smoking marijuana.

He won the 200m freestyle and the 100m butterfly finals on Friday night and took silver behind world record holder Aaron Peirsol in the 100m backstroke final on Saturday. Resuming his search for a third gold medal of the meet last night, Phelps again had to settle for the runners-up spot despite making a concerted push in the second half of the race.

The 23-year-old, who did not swim in the event in Beijing, finished in 49.04sec while Bousquet clocked a meet record 48.22sec.

Asked how he felt about his performances at the meeting, Phelps admitted: "I'm not disappointed with my times but my finishes were awful.

"So there are small things I need to work on but overall it was a pretty good meet.

"I didn't expect some of these times but I'm back on track and from here I head to the US Olympic training centre at Colorado Springs for three weeks and I'm looking forward to that."