LAURA Muir blamed her post-Olympic hangover for her lowest finish in any race for over seven years, conceding it was “not a good day at the office.”

The 28-year-old came 12th in the 1500 metres at the Prefontaine Classic in Oregon in 4:05.92, over ten seconds slower than the British record that earned her silver in Tokyo just 15 days before.

In the stadium where she plans to hunt a world championship medal next summer, the Scot was tracking Olympic champion Faith Kipyegon. But she ended almost the length of the home straight adrift as the Kenyan’s world record attempt at the Diamond League leg fell just short with a time of 3:53.23.

Muir said: “I went for it at the start and it was a really fast pace. I thought I might as well go for it but the Olympics took a lot out of me and the jet lag as well. I just hit a bit of a wall half-way through the race. But I gave it a good shot. I’m home in one piece and I’ve got a got a few races left this season.”

Next stop: Paris for Muir who will move up to 3000m for next Saturday’s outing in the French capital. But racking up the air miles on her post-Tokyo tour has come at a price, she admits.

“I’ve just been trying to recover from jetlag. It’s an eight-hour time difference to back home. I adjusted there but then had another eight-hour time difference to come here. So I was trying to get over 16 hours of jetlag. I was trying to get back into training but things have caught up with me a little bit. I know I’m in good shape.”

Training partner Jemma Reekie slumped to eighth in the 800 metres in 2:00.27 in her own post-Tokyo crash.

The 23-year-old, fourth at the Olympics but ranked number one in the world, was second at the bell but was swallowed up by the chasing pack as golden girl Athing Mu powered clear to lower her American record to 1:55.04.

“I knew this was probably going to be a little tougher because coming off the Olympic Games and running a personal best there,” said the 19-year-old, who claimed two golds in Japan. “So I wasn't looking at times, I just wanted to come here and run with whoever is out there and just be competitive.”

Elsewhere, Britain’s Dina Asher-Smith was third in the 200 metres in 22.19 secs while fellow Olympic medallist Holly Bradshaw came second in the pole vault. Norway’s 1500m Olympic champion won the mile in the ninth-quickest time in history of 3:47.24 with Welshman Jake Heyward sixth.