(CNN)It's a record that's stood for almost six years.
The 9.58 seconds run by Jamaica's Usain Bolt in the 100 meters in 2009 has been the benchmark for international sprinters, and it has rarely looked like being broken -- until Justin Gatlin clocked 9.74s earlier this year.
That's quick -- very quick -- given that the American, twice banned for doping, is now 33.
Despite Gatlin's scintillating form this season -- he has recorded personal bests in both the 100m and the 200m -- world and Olympic champion Bolt is in bullish mood.
Until Friday, when Bolt ran 9.87s in the Anniversary Games at London's Olympic Park, he had not cracked 10 seconds this year.
"I don't think he is going to break my record," he responded matter-of-factly when asked about Gatlin ahead of the Anniversary Games. Gatlin was not invited to take part due to his past suspensions.
"I never worry about one person," added Bolt, who has struggled with injury this season. "You can't sit and worry about one person ever. All I do in a day is just train hard and just try to get on the right page."
In 2006, Gatlin was given an eight-year ban after testing positive for testosterone. The suspension was halved following his cooperation with the U.S. Anti-Doping Agency (USADA).
According to USADA figures, the former world and Olympic 100m champion has been tested 59 times since his return to athletics in 2010. Gatlin won bronze at London 2012 -- where Bolt completed his second successive Olympic treble, winning 100m, 200m and 4x100m relay gold medals.
"There will be no response from my client Justin Gatlin," said the American's representative Renaldo Nehemiah when CNN contacted him for a response to Bolt's comments.
Previously the U.S. sprinter has vehemently denied ever knowingly taking a banned substance and earlier this year, Gatlin said he didn't understand why he was often referred to as a "two-time drug cheat" -- a reference to his first ban after he tested positive in 2001 for an amphetamine found in attention deficit disorder (ADD) medicine he had taken.
"Other people in the sport have taken the same medication I had for ADD and only got warnings," Gatlin told Reuters as he spoke about the two-year ban that was later reduced to one. "I didn't."
And he told British newspaper the Guardian in May that he tested positive in 2006 because his massage therapist rubbed a testosterone cream on him without Gatlin's knowledge -- a claim the therapist denies.
However, given Gatlin has served two bans, CNN correspondent Amanda Davies asked Bolt whether his rival was worthy to break his world record.
"It's a tough question," said Bolt. "If he did it clean, sure. If he didn't, no. Who's to tell, right? But I don't think he's going to break it. And if he does, I'll break it back," added Bolt with a confident laugh.
Gatlin is the only man to run 9.80s or faster in the 100m since 2014 and has done so six times.
But the 28-year-old Bolt -- now with Friday's 9.87 under his belt -- is backing himself to come good at next month's world championships in Beijing.
"You can never doubt yourself. I've been in these situations a couple of times where leading up to the championships I've not been competing at my best," he said.
"But I know when it comes to the championships I have a different mindset going into them, and when I get there my whole vibe just changes.
"I'm never worried. I know Gatlin is running fast, he's going great. But I know when I get to the championships, I'll be ready."
Bolt says he has been the subject of an increasing number of doping tests.
"I think especially in Jamaica I've really been tested a lot by my own federation now, because over the years they've changed the system and they've really done a few blood tests also," he said.
"I've been tested a lot this season. I have no problem. I really enjoy when they come test me on a regular basis. It helps the sport and it shows that I continue doing what I do clean."
Yet Bolt admitted that regulators such as athletics bodies and the World Anti-Doping Agency face an uphill task in their attempts to win the doping war.
"The person, if they're going to cheat, they're going to cheat. I think it's just one of those things -- I think it's just your personality," he said.
"Because a lot of people know the punishment, say, for killing or whatever. But they still do it.
"So I think it's all about the personality, sometimes. People, they will cheat. So it's all about making the bans harsher to make them really second-guess themselves or think about it."