The reigning Dakar champion remained with Marcic for some time after the collision, awaiting the arrival of the medical helicopter before continuing on with the stage.
He finished the test 6m45s behind nearest rival Sebastien Loeb, but was given 14m13s back by organisers.
As such, he has inherited the stage win and now leads Loeb by 5m50s with two days and 306 timed kilometres to go.
Speaking to the media after he completed the stage, a visibly shaken Peterhansel said the incident could have been fatal for Marcic.
Recounting the crash, he said: “I was lost and he was lost. It was in the rio [riverbed] but not a good rio.
"Everybody was lost. I was not really fast, probably 60 km/h, but it was some vegatation, so it was not possible to see him.
“He was also not really fast, maybe 40km/h - but suddenly when he saw me, he braked really hard and he crashed. I braked also really hard but I was not able to change direction. I stopped. The impact was not really strong but he was under the car.
“My co-pilot [Jean-Paul Cottret] went out of the car, checked the situation. I put on the reverse [gear], and he [Marcic] was okay.
"He had a really big impact on his leg, but his head was okay, was clear, he was completely clear. And he said directly 'I have the leg broken'. We stayed, I don't know, probably 15 minutes with him, we waited for the medical helicopter.
“It was just that navigation was really complicated and a lot of possibility to lose the good rio. It's not a problem from the organiser, it's just that they wanted to do a really complicated stage and with this complicated stage everyone was lost.
“After we had the accident with the biker, after I saw maybe 20 bikers arriving from the opposite direction. After that it was very complicated to be focused on the track.
“In the end, it's only a leg broken - but if I touched, for example, the head of the guy, it could've possibly killed the guy.”