The 33-year-old lost out 6-0 6-3 to fellow countryman Ivan Dodig but admitted that his head wasn't really focused on the game.
"It was a tough day for me, on the court and off," said Ljubicic. "I had my mind everywhere else except on the tennis court. Obviously I'm completely out of shape. I don't even think it makes any sense to talk about the match today.
"I have to say that I felt like it could end up emotionally but I didn't expect these big emotions really. It's the end of something beautiful for me. It's been 20 years and now it's time to do something else."
Ljubicic's best result at a grand slam was reaching the French Open semi-final in 2006; he reached a career-high ranking of three in the same year.