This is one of the feel-good sporting stories of 2016.
Jonny Brownlee, silver medalist at the 2016 Rio Olympics, was struggling badly in the final straight of the Triathlon World Series in Mexico and appeared to be on the verge of collapse.
The 26-year-old, who was leading the race, had nothing left to give and a member of the staff stepped in and helped him stay on his feet with just 700m left.
Moments later, Brownlee’s brother Alistair caught up with his sibling and saw he was in trouble.
But rather than overtake Jonny, Alistair put his brother’s arm around him and the pair raced towards the finish line together. (Scroll down to watch the video).
Video: Alistair helps Jonny over the finish line
Alistair then threw his exhausted brother over the finish line in second place before watching him collapse in a heap.
South African Henri Schoeman won the race, but it’s the Brownlee brothers who have captured the world’s hearts.
The world reacts
Here’s how Twitter reacted…
Alistair: I wish the idiot has paced it right!
Alistair claimed it was "a natural human reaction" to come to the aid of his struggling brother, telling BBC Sport: "I'd have done the same thing for anyone in that position."
He added: "I wish the flippin' idiot had paced it right and crossed the finish line first.
"He could have jogged that last two kilometres and won the race.
"You have to race the conditions. I was comfortable in third. I raced the conditions, I took the water on, made myself cool and I was all right."
Jonny thanks his brother from hospital
Later on, Jonny posted a tweet from his hospital bed, praising his bother.
“Thanks @AliBrownleetri,” he posted, “your loyalty is incredible”.
Be honest: would you help your siblings in the same way? Have your say by leaving a comment below.