The peloton were speeding towards the end of the first stage of the Arden Challenge in Belgium on Saturday when the shocking moment occurred.
Footage shared on social media showed the horse running to catch the back of the group as they passed through a grassy area.
As the horse came off the grass and continued its dash towards the riders, the peloton picked up the pace to get away from it.
But with a number of cyclists beginning to look back in a state of panic, one rider took control of the situation.
Belgian Lars Daniels, 23, started putting his arm out in an attempt to tell the horse to stop.
He then dropped off the back of the bunch and began waving the horse down, before he got hold of its reins and brought it under control.
Daniels then cycled back up to the peloton and finished with the group.
Reacting on X, one person joked: “A hero without a cape.”
Another added: “The UCI would be able to impose a penalty or disqualify him for holding on to the horse and being towed.”
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While a third replied: “Wout Van Aert would have finished on the horse and taken it 650km to the finish.”
Daniels’ best finish in the Arden Challenge came in the fifth and final stage when he placed ninth.
Dutchman Arno Wallenborn claimed the general classification.