(CNN) -- Former world number one Lleyton Hewitt fell victim to eighth seed Yen-Hsun Lu of Chinese Taipei in the first round of the ATP tournament in Delray Beach, Florida.
Hewitt is battling back to full fitness after undergoing hip surgery last year.
Hewitt, coming off a semifinal exit in Memphis to eventual winner Andy Roddick, was beaten 7-5 2-6 6-2 by the improving Lu, who shocked David Nalbandian at the Australian Open.
The Australian levelled at one set all, but fell an early break behind to Lu in the deciding set.
Hewitt, who had hip surgery last August, broke back to trail 3-2, but could not sustain his effort and did not win another game as he went out in just under two hours.
Hewitt, who was celebrating his 28th birthday, won the Delray Beach tournament in 1999.
Earlier, Cypriot Marcos Baghdatis upset third seed Ernests Gulbis of Latvia 7-5 6-2 to continue his improvement after injury problems limited him to 12 tournaments in 2008.
Top seed Mardy Fish advanced with a 7-5 6-3 win over Canadian Frank Dancevic to earn a clash with veteran Vince Spadea, who beat German Denis Gremelmayr in three sets for his first win this season. However, 2006 Delray Beach champion Tommy Haas went out -- beaten 7-6 6-3 by French seventh seed Jeremy Chardy.