Mo Farah believes Joshua Cheptegei will be his main rival again in 5,000m

• ‘The new, raw athletes are scary,’ says Briton before Wednesday’s heats
• Farah would be surprised if team-mate Andy Butchart won a medalMo Farah believes his big-race experience will carry his battered and bloodied body to yet another world title in the 5,000m – but admits he will again be looking over his shoulder at the brilliant young Ugandan Joshua Cheptegei, who ran him so close in Friday’s 10,000m final. Related: Mo Farah says it was his ruthless