After the final climb, the first year Sunweb professional powered to the line in Quriyat, beating Rui Costa (UAE Abu Dhabi) and race leader Ben Hermans (BMC).
The overall leader’s red jersey remains on the shoulders of Hermans before the two decisive stages of this 8th edition including the climb up Green Mountain on Saturday.
"The team was amazing again today,” Andersen said. “They delivered me to the bottom of the climb as fresh as possible.
“After their great work it was up to me to finish the job. I started the sprint with 250 metres to go and from then on rode full gas. It was an incredible feeling to cross the line in first place. It was a great team effort and great legs and one I will remember."
The 162km stage from Sultan Qaboos University to Quriyat began with a break featuring six riders who were kept under control by the peloton before they were caught with 17km left to race.
On the final climb just on the outskirts of Quriyat, Julian Arredondo (Nippo-Vini Fantini) was the first to give it a go in the last 2km. He was soon caught and distanced by Laurens De Plus (Quick-Step Floors) who could enjoy a eight second lead with only one kilometre to go.
De Plus remained alone in front in the closing moments but was caught by the group of favourites including 30 men. As on the previous day, timing was essential, as Andersen powered to the finish ahead of Costa and Hermans.
Hermans remains in the overall lead with a two-second advantage over Costa and 10 seconds over Jakob Fuglsang (Astana). He leads points classification while the rider in fourth place overall, Merhawi Kudus (Dimension Data) holds the best young rider’s jersey.
“I’m confident that I can hold onto the jersey,” Hermans said. “Two days in red is already a good result. We hope for a stage win with Greg (an Avermaet) so hopefully that may come tomorrow.
“Rui Costa is more of an explosive rider but you can see that I can be with him on these kind of climbs, so on a longer climb like Green Mountain, I think it will be more Merhawi Kudus (Team Dimension Data) and Romain Bardet (AG2R La Mondiale) who I have to look out for.”