"My run felt good for the most part and I was on a par with (Slovakian top qualifier) Jakub Grigar for three-quarters of the run, just losing time in the up-stream gate 8 and the double-up through 16 and 17.
"It's awesome to know that I can fight it out and be in the mix, though, and even with a big mistake and a touch, I was sitting just out of the final."
Gilbert also picked up a touch, on just the second gate, and had to play catch-up the whole way down the Wisla River course just out of Krakow. Without the touch, he would've also sneaked into the top-10, in 10th spot.
"The course today was really tricky, with plenty of tight moves, which made for some exciting racing," Gilbert said. "I didn't find the rhythm in my run today, but I've had a great season so far and am looking forward to heading home for a break before coming back to Europe to race the final two world cups."
The Kiwi pair were in good company as reigning open and under-23 world champion Jiri Prskavec (Czech Republic) also missed the final, finishing 25th.
Mutton, meanwhile, picked up plenty of experience in his semifinal run, with several years still left in the junior division.
His 98.13sec time included three touches, putting him 11secs behind top qualifier Felix Oschmautz (Austria). Fellow Kiwi Callum Aitken was 24th, another second back.
The New Zealand female K1 charge faltered a day earlier, with Anna Higgins, Courtney Williams and Kaydi O'Connor-Stratton missing the semifinals in the under-23 division and Kensa Randle dipping out in the juniors.