The Californian-based rider had a poor quarter-final but qualified in third place before nailing his gate on his way to win his semifinal.
Willers was a fraction off out of the gate in the final but cut back under Strombergs on the first corner to push up to third. He then tried a similar manoeuvre on the next corner on Daudet but clipped the Frenchman's back wheel and crashed, bringing down two other riders.
"Out of the start I felt someone blow straight into me and I didn't get down the hill as fast as I wanted," Willers said. "I thought I could push into that last turn but Joris (Daudet) saw me coming at the last minute and cut over and I went down instead of him.
"I just didn't want to settle for another third place. I figured I had a chance of second and had a go. Second's as good as last so I thought it was worth going for.
"I've got to nail my consistency more. I started the day off great, then had a bad one in the quarter, a great one in the semi and a not so great one in the final."
Australian Sam Willoughby took out the world title, with several top hopes missing out on the final and time trial winner Connor Fields (USA) crashing.
Walker, who has only been back on her bike for a week and had not practised on the high start ramp before Birmingham, was greatly relieved with the Olympic dream in jeopardy.
She jumped out of the gate to trail home eventual world champion Magalie Pottier (FRA) in all three of her qualifying motos, and again in the all-important quarter-final, where she led to the first corner.
Walker again gained a good gate in the key semifinal, and while she was muscled out on the short first corner to finish one spot out of the final, Walker was nonetheless relieved to have handled the pressure with the Olympic qualifying spot on the line.
"I know now that I can perform under pressure and that's really good for me for London," Walker said. "The pressure was on in the quarter because if I didn't make it out of the quarter then that was my spot gone. And there was pressure not to crash out in the semifinal so I had to stay on my bike and ride smart.
"Performance-wise I am ecstatic considering I've been a week back on the bike and managed to get the hole-shot (first to the first corner) against the best riders in the world. Once my fitness is back up to where it was before the accident and a lot more hard work, then I'll be confident of my chances."
There were plenty of upsets, none more so than former world champion and major British hope Shanaze Reade, who crashed while leading in the quarterfinal.
Promising Kaiapoi rider Trent Jones had to settle for fifth place in the junior elite men's final after winning his semifinal.
The sole medal for the New Zealand team today went to another North Canterbury rider in Rangiora's Tahlia Hansen in the 15-years challenge class, with age group racing staged alongside the elite finals day.
Hannah Sarten (New Plymouth) was sixth in the 16-years girls and Cody Merito (Te Awamutu) eighth in the 15-years finals.
The championships will be completed with Challenge (age group) racing tomorrow in the Cruiser class, for the larger 61cm wheel base bikes.
Results:
Elite men quarter-finals heat 1: Nic Long (USA)1, Dave Herman (USA) 2, Sifiso Nhlapo (ZAF) 3, Brian Kirkham (AUS) 4. Heat 2: Maris Strombergs (LAT) 1, Quentin Caleyron (FRA) 2, Marc Willers (NZL) 3, Anthony Dean (AUS) 4. Heat 3: Corben Sharrah (USA) 1, Joey Bradford (USA) 2, Donny Robinson (USA) 3, Josh Meyers (USA) 4. Heat 4: Joris Daudet (FRA) 1, Moana Moo Caille (FRA) 2, Sam Willoughby (AUS) 3, Tyler Faoro (USA) 4.
Semifinals, heat 1: Willers 1, Herman 2, Strombergs 3, Dean 4. Heat 2: Willoughby 1, Daudet 2, Robinson 3, Moo Caille 4.
Final: Willoughby 1, Daudet 2, Moo Caille 3. Also: Willers 7.
Elite women, quarter-finals, heat 1: Magalie Pottier (FRA) 1, Sarah Walker (NZL) 2; Stefany Hernandez (VEN) 3, Caroline Buchanan (AUS) 4. Heat 2: Manon Valentino (FRA) 1, Mariana Pagon (COL) 2, Laura Smulders (NED) 3, Arielle Martin (USA) 4. Heat 3: Vila Rimsaite (LTU) 1, Romana Labounkova (CZE) 2, Sandra Aleksejeva (LAT0 3, Squel Stein (BRA) 4. Heat 4: Alise Post (USA) 1, Eva Ailloud (FRA) 2, Lauren Reynolds (AUS) 3, Maarje Hereijgers (NED) 4.
Semifinal 1: Pajon 1, Valentino 2, Pottier 3, Martin 4. Also: Walker 5. Heat 2: Post 1, Labounkova 2, Ailloud 3, Stein 4.
Final: Pottier 1, Ailloud 2, Labounkova 3.
Junior men, semifinals, heat 1: Trent Jones (NZL) 1, Jasper Peters (NED) 2, Karl la Nagard (FRA) 3, Julian Schmidt (GER) 4. Heat 2: Carlos Ramirez (COL) 1, Maliek Blyndloss (USA) 2, Leopold Tramier (FRA) 3, David Lopera (COL) 4.
Final: Ramirez 1, Blyndloss 2, Tramier 3. Also: Jones 5.
Junior women final: Felicia Stancil (USA) 1, Nadja Pries (GER) 2, Dani George (USA) 3.
Challenge class finals:
Girls 15 years: Charlotte Devolder (FRA) 1, Tahlia Hansen (NZL) 2, Valerie Sebrovkova (GBR) 3.
Boys 15 years: Colin Hudson (USA) 1, Quentin Hubert I(FRA) 2, Romain Racine (FRA) 3. Also: Cody Merito (NZL) 8.
Girls 16 years: Carlie Ferree (USA) 1, Shealen Reno (USA) 2, Sarah Sailer (GER) 3. Also: Hannah Sarten (NZL) 6.
