Just as the race seemed to be settled, the Californian made his charge in what was a seriously exciting finish.
In the shakeout of 12 riders all hungry for the podium, it was 15-year-old Italian Kevin Calia who scraped into second and the 15-year-old Italian-Nigerian Alessio Cappella finished third. Britain's Harry Stafford was fourth and Japan's Daijiro Hiura, the pole sitter, had to settle for fifth. Gagne's victory vaulted him into fourth place in the standings.
Calia, Cappella and Hiura were all in the lead and in contention coming into the final corners when Gagne made his bid in what was a flash of tactical brilliance. "I was in the group, it was pretty hard and there was no point in trying to lead early on, no one was getting away," he said.
"About five laps to go I started to push forward, I didn't want to be too far back when it came to the end. Then one the last lap I got the perfect slipstream into the lead and just had it pinned through the last left down to the chicane." Gagne said. ""I was pretty confident that I was quick through that last corner, I could lead down to it I was pretty sure I could win as long as I didn't make a mistake. I was deep on the brakes but it worked out OK."
Calia and Cappella traded the lead for most of the race with early challenges by Swede Alex Kristiansson. Calia had some anxious moments when a seagull landed on the track in the last lap but said he was happy to be second and pledged to do better in Saturday's race. It was also Cappella's first visit to the podium and his race was punctuated by some slick inside passes in the corners.
Stafford was also well in the running for the top spot but said riding in such a compact leader group made it difficult to break away. "I was right there and I thought about trying to win it on the brakes to the last chicane but there was a whole group of us and it was too risky, too much chance of crashing and taking other guys out. It was a rough race but a lot of fun and I can't wait for tomorrow," he said. Hiura may have missed the start after having secured the coveted pole but he was right up with a chance of the top spot in the final flurry of track action.
The traditional Dutch circuit hosts a second race in the series on Saturday at 15.40 CET and can be viewed on live streaming on Red Bull Rookies TV.
Race One Result (Assen)
1. Jacob Gagne (USA) 29 minutes 10.553 seconds (149.449 kph)
2. Kevin Calia (ITA) +0.078
3. Alessio Cappella (ITA) +0.124
4. Harry Stafford (GBR) +0.296
5. Daijiro Hiura (JPN) +0.371
Championship standings
1. Daijiro Hiura, Japan, 72 points
2. Danny Kent, Britain, 63
3. Daniel Ruiz, Spain, 59
4. Jacob Gagne, USA, 54
5. Mathew Scholtz, South Africa, 41