Mo Farah calls time on track return and targets 2020 Olympic marathon

• Briton concedes he may never run a track race again
• Farah beat Andy Butchart in Vitality London 10kmMo Farah has conceded he will almost certainly never run a track race again and said his sights are now firmly on running the Olympic marathon in Tokyo.Speaking after winning the Vitality London 10km on Monday ahead of Andy Butchart, Farah admitted that, while he had wanted to defend his world 10,000m title in Doha, he had changed his mind because it was too close to the Chicago mara