|World Athletics Championships on the BBC|
|Venue: London Stadium Dates: 4-13 August|
|Coverage: Live across BBC One and Two, BBC Radio 5 live, BBC Radio 5 live sports extra, the BBC Sport website and app.|
Usain Bolt is a genius and has had as big an impact on athletics as Muhammad Ali did on boxing, says Lord Coe.
Sprint legend Bolt, an eight-time Olympic gold medallist, is set to retire after the World Championships in London, which begin on Friday.
Coe likened the Jamaican, 30, to former world heavyweight champion Ali, one of sport's most iconic figures.
"He is the best sprinter of all time," said Coe, who is president of the sport's world governing body the IAAF.
"Usain Bolt is a genius. I can't think, other than Muhammad Ali, of anybody that has so had an impact inside or beyond their sport.
"You can have the Friday-night-in-the-pub conversations about who is best footballer or tennis player, but there is no argument about this guy in sprinting."
Bolt won 100m, 200m and 4x100m gold at the past three Olympic Games - Beijing 2008, London 2012 and Rio 2016.
However, his unprecedented 'triple triple' of nine gold medals was downgraded to eight after Jamaican team-mate Nesta Carter, part of the quartet who won the 4x100m in Beijing, tested positive for a banned substance. Carter has appealed against the decision.
Bolt is also an 11-time World Championship gold medallist, and has won the 100m title three times.
"We shouldn't be sitting there saying you are suddenly going to find another Usain Bolt any more than just boxing suddenly found another Muhammad Ali," Coe told BBC Sport.
"What we will miss is the personality. We do want athletes with personality. It's nice to have someone who has a view and fills the room and fills a stadium.
"We are not going to replace Usain Bolt - not because you are not going to have a trophy cabinet full of three back-to-back Olympic doubles and relays and World Championships - you are just not going to replace him because his personality dominated not just our sport but pretty much every sport out there."
Coe, who won Olympic 1500m gold in 1980 and 1984, said it would be "virtuous" for both Jamaica and global athletics to keep Bolt involved in the sport after his retirement and that "discussions" had taken place.
'Athletics in transition period'
Like Bolt, long-distance champion Mo Farah will race on the track for the last time this month. The Briton, who will defend his 5,000m and 10,000m world titles in London, will make his final track appearance in Zurich on 24 August before switching his focus to marathons.
"You are not going to replace them," Coe told BBC Sport, adding he wants to help give other athletes the platform to "tell their own story".
"Everyone knows Usain Bolt but, if you start talking about some of our other extraordinary talents in the sport, some of them are walking through their own towns in anonymity let alone the global stage."
Farah, 34, has won the 5,000m and 10,000m titles at each of the past two Olympics.
Coe believes Farah's departure from the track - along with heptathlete Jessica Ennis-Hill's retirement, and long jumper Greg Rutherford's injury problems - also leaves British athletics in a transitional period.
"If you look at the medals British athletes have won in the past two or three Games, the bulk have come from three competitors so we need to spread that a little wider," he said.
What about the issue of hyperandrogenism?
The IAAF said last month it could reinstate gender tests for female athletes with high levels of testosterone after a new study found it gave them a "competitive advantage".
The Court of Arbitration for Sport (Cas) suspended the IAAF's hyperandrogenism rules for two years in July 2015, and gave the governing body until July 2017 to justify reinstating them.
"We've got to do it in a way that doesn't demonise athletes," Coe said. "This is a sensitive issue.
"It is my responsibility that we settle upon something that gives female athletes comfort that they are competing on a level playing field.
"Cas has asked us to go away and to present the science on this. This we will do."
Russia remains banned from competition
The IAAF has voted unanimously to maintain Russia's ban from international track and field competition as there are still issues that need to be resolved regarding the country's anti-doping fight.
Russia was accused in a World Anti-Doping Agency report last year of widespread state-sponsored doping. Its athletics team was barred from last summer's Rio Olympics and will also miss the World Championships.
"Material progress has been made but there are still issues that need to be resolved," said Rune Andersen, independent chairman of the IAAF taskforce looking into doping in Russia.
"I can confirm that our impression is that they really want to meet all the criteria that has been set.
"The main issue is that no meaningful testing is being conducted."
Andersen said the Russian anti-doping agency is still not code-compliant and that Russian authorities must acknowledge the outcome of the McLaren report into doping in the country.
"It's difficult to get an excuse, but we need some sort of an explanation on how they deal with this report in the most effective way," he added.
Nineteen Russians will compete as neutrals in London and Andersen said he had noticed an encouraging change in culture "starting with the athletes".
However, he added there was still an issue with banned coaches continuing to operate freely, and stuck with the timeline of a Russian return to international action in November.