CHARLOTTE: US swim superstar Michael Phelps has become far more guarded in social settings and wary of strangers since a photograph of him holding a marijuana pipe became a global sensation in February.

In his first public comments since the frenzy and a subsequent three-month suspension from USA Swimming, Phelps said Thursday on the eve of his first meet since the Beijing Olympics that his life will never be the same again.

"Wherever I go I'm very aware of literally every thing around me," Phelps said. "I'm checking it more regularly. I'm constantly scanning the area and if I'm not comfortable then I'm not staying there." Phelps repeated the apology he made after being photographed holding a 'bong' which is commonly used for smoking marijuana and gave a hint of how betrayal by people he had considered friends has impacted his life in the wake of the incident.

"It was bad judgement and a stupid mistake, something I have learned from and continue to learn from. I hope I can keep more people from making the same mistake," Phelps said.

"You always have to be aware of who your real friends are, who is around you for you who are instead of what you've done. Your guard always has to be up." While Phelps said he was unsure if the public would ever forgive him, coach Bob Bowman, who has guided Phelps in the pool since childhood, said the memory of a record eight gold medals at the Beijing Olympics carries more weight.

"He's the greatest Olympian of all time. That's how I will remember him and judging by the reactions from fans as we're walking down the street, that's how the public remembers him as well," Bowman said.

"It's amazing. He doesn't go anywhere where he isn't recognised all the time." Paranoia is not setting in. Phelps is not confiscating cellular telephones for fear of unwanted snapshots. But Bowman notices a change.

"I don't know if his personality has changed," Bowman said. "When he's around people he doesn't know, he is more careful. A little healthy skepticism is good for him." But concerns he might snub the 2012 London Olympics because it was a British tabloid newspaper that published the photo are unwarranted, Bowman said.

"I don't think Michael has any resentment at all for the British people," Bowman said.

Phelps, who also won six gold medals at the Athens Olympics, was on a whirlwind appearance schedule after Beijing that even he never expected.

"I had no idea what to expect," Phelps said. "It has been absolutely nuts, good times and bad times." Not until waking up on March 1 did Phelps decide to push himself for another four-year training cycle.

"I was the only one who could make that decision," Phelps said. "When I woke up that Sunday I knew I still wanted it." Bowman was less worried about Phelps's choice than having him make a careful one in the wake of the unwanted publicity and suspension.

"I was most concerned about him regaining his balance and making a smart decision," Bowman said. "I said if he wanted to come back it should be because he wants to and not to make up for something else." With Phelps now linked in gossip rumours to controversial beauty queen Carrie Prejean, he has learned the price of fame means unwelcome attention.

"There are avenues on the internet where people can say what they want to say and not have to back it up," Bowman said.