Mo Farah back with a bang as he takes 5,000m in Lausanne

Running it seemed with extra spark and perhaps a little anger Mo Farah is back, winning the 5,000 metres at the Lausanne Diamond League with an astonishing finishing sprint that appeared to surprise even himself, it not then certainly delight him.

That’s because Farah briefly looked beaten, when Yomif Kejelcha from Ethiopia, still officially only 17, cruised past Farah down the backstretch, opening a gap of a couple of metres. Then, into the homestretch, Farah kicked past, gesturing to the crowd to raise some further noise as he took the win in 13:11.77. His last lap was 54.44 seconds.

It was Farah's first race since the BBC Panorama documentary, aired at the start of June, raised serious allegations of doping practices by his coach, Alberto Salazar. Whatever about the enduring implications of that, the British athlete is clearly back to his best, or perhaps even better.

The race was suitably loaded – billed as a sort of preview to next month’s World Championships in Beijing – and while Farah looked perfectly composed for most of the race, he doesn’t normally let athletes past him on the last lap. He briefly looked spooked.

Still, Farah had lost just one previous 5,000 metres in the last five years (and that was in Eugene, in 2013, when he was sick), and has also dominated the distance at the last three global championships. The only question about this race was what challenge Caleb Ndiku, the man Kenya believes will dominate the distance in the coming years, might have made, had he not fallen with just over one lap to go.

Largely tactical, they passed 3,000m in 8:04, Farah then hitting the front until Kejelcha made his move. But the Ethiopian, the athlete in form and with a 12:58.39 already this season, had no answer once Farah kicked past, the last 50 metres all about as much celebration Farah could pack into it.

There was another fantastic 800 metres, where David Rudisha once again found his dominance taken out by the young Nijel Amos from Botswana, who edged past the Kenyan in the last 100 metres to take the win in 1:43.27.

The other main attraction was to be Usain Bolt, originally down to race the 100m here, only to withdrew last week, with a leg injury – and perhaps just as well. Even at his best Bolt would have struggled with the increasingly incredulous dominance of Justin Gatlin, who took another win here in 9.75 seconds, just off his lifetime and season best of 9.74.

One again Gatlin defied his 33 years to beat the best around, the two-time doping offender never threatened. The two men left chasing are also not long back from doping bans, with fellow American Tyson Gay given the same time as Asafa Powell from Jamaica in second, 9.92 seconds, although Powell was given second on the photo.