New Zealand's Brendon Leitch has taken a breakthrough first race win in the F4 US Championship, following a chaotic, rain-affected opening race at Mid-Ohio.

"I'm pretty stoked, it's been a long time coming to get a win over here in the series," Leitch told Herald.co.nz.

"I thought I'd come over here and do a lot better than I have, so it's a good boost. My confidence levels are probably the biggest thing, and to prove that I'm not just another from New Zealand who's come out trying to be the next Scott Dixon."

The ITM pilot started the race from eighth on the grid. On a wet surface, the field had been split almost straight down the middle into cars using slick tyres and cars using wets. Leitch was on slicks, but soon plummeted to 19th.

"We gambled on slicks, about half the field were on slicks. Coming around turn one a guy also on slicks was on my inside and he lost it, and collected me. I spun through the grass.

"At the exit of turn one I thought, 'I've f***ed this, and I'm not going to win the race.'"

Though he was buried in the pack, Leitch had good pace - enough to gain three spots on the second lap of the race. Then a lengthy safety car was brought out, only vacating the circuit with nine minutes of racing left to go.

From there, Leitch pressed on; making plenty of passes and setting the fastest lap of the race on the way. By the penultimate lap, he was up to second place and gaining on the race leader.

"The guy in the lead was on slicks, and I was pulling him in by roughly two to three seconds a lap. I got within six car lengths of him and then there was a torrential downpour on the second to last corner. I saw it and slowed down, but he just went straight into it and into the gravel trap.

"So I just tootled around the last corner and won the race by nearly 10 seconds or something, it was a crazy race."

The win comes at the right time for the Castrol Toyota Racing Series graduate, having endured a difficult debut American season so far; a pair of sixth-place finishes at Canadian Tyre Motorsport Park his best results thus far. Jordan Sherratt and Raphael Forcier rounded out the podium places; Sherratt finishing 9.737-seconds behind Leitch.

Leitch now prepares for race two, where he will start from pole position.

Results (top 10)

1. Brendon Leitch 13 laps
2. Jordan Sherratt +9.737
3. Raphael Forcier +11.026
4. Jim Gaughary Jr. +15.021
5. Ben Waddell +15.478
6. Colin Mullan +16.027
7. Skylar Robinson +19.279
8. Kyle Kirkwood +19.397
9. Austin McCuster +19.944
10. Jacob Abel +24.561