Sir Mo Farah has refused to rule out an Olympic title defence at Tokyo 2020.

The four-time Olympic champion will run in next year's London Marathon, having given up the track last year to focus on the road.

Farah hinted previously he would consider a comeback, although his main focus until April remains the marathon.

But the 35-year-old, who defended his 5,000 and 10,000 metres titles at the Rio Olympics two years ago, has now dropped the biggest hint yet he would be ready to race on the track in Tokyo.

"Yes, there is a chance. There is always a chance if everything is going well," he said.

"Would I turn a medal down, in terms of saying, 'Am I capable of winning that race or could I get a medal?'

"Or would I say, 'I've done that', and turn your nose up at it? I would never do that. You do it any way you can get a medal. Our career is so short.

"You wouldn't turn anything down. I want to collect as many medals as I can and do it for my country."

Farah has previously confirmed he was mulling over a return to the track at next year's World Championships in Doha and said it was still a possibility.

He said: "It's possible to do the 10,000m. I was honest and said I was done with the track, but I look at my team-mates and who I was competing against and part of me missed it.

"I feel like I can still win medals and do as well as I have over the years. If there was a chance to compete, I wouldn't turn down a medal."

Farah won the Chicago Marathon in October, having finished third in London last year, and on Tuesday confirmed he would return to his home race in 2019.

Discussions between the London Marathon and world record holder and defending champion Eliud Kipchoge are on-going, but Farah is keen to race against the Kenyan as he plots his Olympic assault.

He said: "I would be nice to race against Eliud. Can anyone else beat him? I don't think there's anyone who can beat him at the minute. Do I need to up my game and improve to win more races? I most probably need to do that.

"In order to learn and know what he does so well I need to race him more. He is far ahead of everyone else and his record was incredible.

"He's a great athlete. I want to race against him. I can beat him at some point. Will it be in London 2019? I don't know. Will it be World Championships, will he compete? I don't know.

"I'll keep racing until Tokyo 2020 and learn to make mistakes, learn to win races. That's what I need to do."