Byrne had to settle for fourth, though he now moves into the lead of the standings in the absence of Hill, while Laverty and Brookes kept a watching brief in fifth and sixth positions.
More than 13 seconds further back, Jon Kirkham put in a fine ride to claim seventh having started down in 15th position, just ahead of Loris Baz, the Frenchman bogging down at the start to drop from third to a low of 11th before fighting back to eighth position.
Gary Mason was another to make strides up the order for ninth position, while Dan Linfoot ran sixth initially before fading to tenth.
Elsewhere, Alex Lowes put in a magnificent performance on the WFR Honda to finish in 12th place as the top EVO rider. More significantly, however, was his fastest race lap, which puts him second on the grid for race two, alongside pole sitter Kiyonari, Brookes and Easton.
Michael Rutter in 11th, Peter Hickman in 13th, James Westmoreland 14th and Martin Jessopp in 15th made up the remaining points' finishers, while Scott Smart and Barry Burrell joined Lowes on the EVO podium.