It's his first marathon ever, but he's a very experienced runner. It would be hard to find a better prospect for a good first marathon. He's a multiple (former) world record holder and medalist at shorter distances from the mile up to half marathon. His half marathon is still 2nd all time.

I wouldn't have predicted this out of nowhere, but if you told me a marathon debut went this well and asked me to guess whose it was, I like to think I'd have come up with Kejelcha in my top few picks.

That said, great 5000/10000 athletes don't always have great marathon careers. An example from this race is the world record holder at both those distances, Joshua Cheptegei. He's run several marathons but none spectacular by his standards. He was in this race too but 7 minutes back.