Ethan Hayter took bronze for Great Britain in the men's omnium but was left to wonder what might have been on another disappointing day at the UCI Track Cycling World Championships in Pruszkow.

The 20-year-old Londoner rode impressively in the afternoon and led the standings going into the final points race, but tactical errors saw him allow New Zealand's Campbell Stewart and Frenchman Benjamin Thomas to gain a lap on the pack late on.

The move vaulted Stewart into a gold-medal winning position, while Thomas then beat the European champion in the final sprint to snatch silver by a single point.

A frustrated Hayter admitted he had "panicked" when a group of back-markers gained a lap early in the race and let go of his tactical plan.

"I let it get to my head a bit," he said. "Normally I'm quite clever, I follow a lot of the right moves but early on I did way too much.

"I panicked when that lap went, I didn't realise that was I was still in the lead after that lap got taken. I'd already panicked and spent too much gas there.

"I just missed that zip after that to nip on to moves, I'm normally quite good at nipping on to moves and following. My decision making went out the window. I guess it's inexperience."

Neah Evans and Elinor Barker had to settle for fourth place in an eventful Madison race, in which Evans was one of several riders to hit the deck in her world championships debut.

The British duo won two sprints to keep themselves in contention for bronze until the end, but the Danish duo of Amalie Dideriksen and Julie Leth took the points on the line to claim third place, while Kirsten Wild and Amy Pieters took gold for Holland.

Barker had only been drafted into the team in the morning, taking the place of defending champion Katie Archibald who crashed heavily in Friday's omnium – having herself stepped into that event as a late replacement for the ill Laura Kenny.

The domino effect was keenly felt.

"It's so frustrating," Evans said. "In training we know we're strong, and we know we've done a lot better than we've done today."

Evans spent a month working on the fine details of the race with Archibald, but the late switch meant all that was boiled down into a crash course for Barker after breakfast on Saturday morning.

"We watched a year's worth of videos and I tried to kind of absorb it all," said Barker, a European champion in the event in 2017.

"I don't want to use it as an excuse because obviously I've ridden a lot of Madisons before and I'm relatively experienced. It's just mentally having your head in the game."

There was frustration in the men's sprint too as Joe Truman won his 1/8 final against Nathan Hart, only to be relegated for riding on the blue band at the bottom of the track, the commissaires ruling he gained an advantage by cutting a few metres of the final corner.

"He's upset," said sprint coach Justin Grace. "Especially when he won the race, it's tough for him and he'll have to go away and reflect on that.

"Did it affect the outcome of the race? In our opinion, no. But did he break the rules? Yes. In 30 years of being involved in racing I've never seen a sprinter rubbed out for doing that."

Shortly before Truman was relegated, last year's silver medallist Jack Carlin lost his heat against Russian Denis Dmitriev, while neither Katy Marchant nor Vicky Williamson made it out of qualifying for the women's 500m time trial in the morning.

It summed up a frustrating week for both sprint squads in Poland, with fifth place for Carlin in the keirin their best showing so far and only the women's keirin to come on Sunday.

"There are no excuses," Grace said. "We know we've got good riders and we know they're in pretty good shape but we haven't executed very well this week."