Shane Byrne was denied the chance of victory at Snetterton after a collision with title-rival John Hopkins in race two on Sunday.
Byrne had fought his way into the lead on the HM Plant Honda bike but collided with Hopkins after the American tried to pass him on the penultimate lap.
The Sittingbourne rider, who needs podium credits to give himself a good chance of title ahead of the final three round showdown, had to settle for fourth and was bitterly disappointed.
"I felt we had the pace to challenge for the win," he said.
"I was obviously disappointed to be taken out. He (Hopkins) has since apologised but I was a bit gutted really as I thought I could have won."
Ryuichi Kiyonari took race two victory after taking full advantage of the clash for the lead.
Byrne had earlier claimed a third place finish in race one, having started sixth on the grid.
It was Byrne’s ninth podium finish of the season, but is now just one credit ahead of Hopkins. In the final three rounds rider standings revert to podium credits.
Byrne said: "In the beginning of the race I was feeling really comfortable and was in touch of John (Hopkins) and Tommy (Hill). It was the first time I had done a long race run though and I was struggling with tyre longevity over the final laps.
"They were ahead and after the safety car I thought that it was better to take third and a podium credit than end on the floor with a crash."
Byrne remains ahead on points in the championship, leading Hopkins by 19 points. Round seven takes place at Outlon Park in a fortnight.