Points-leader Ken Roczen finished fourth after he got tangled up with Webb on the start, shuffling him back to seventh.
Down in the 250SX Class, Cameron McAdoo won his first career race, passing rookie Stilez Robertson with five minutes to go and pulling away for the 3.6-second victory.
The red flag was displayed for about five minutes during the second 250 heat after a nasty wreck by Ryan Sipes on the first lap.
Following the heats, respective Last Chance Qualifier (LCQ) races advanced the top-four finishers from each into the main events.
Hardy Munoz won the 250 LCQ, which featured a pair of red flags that reset the 5-minute clock each time, while Dean Wilson was the 450 winner.
DeLand's Justin Starling, who started his own team this season, fell one spot short of advancing in the 450 LCQ.
- Eli Tomac ties Ricky Carmichael at Daytona in Supercross Round 9; Ken Roczen calls out Cooper WebbNBC Sports - Motorsports
- 2021 SUPERCROSS SEASON POINT STANDINGS AFTER ROUND 9Motocross Action Magazine
- Cooper Webb charges to a fourth consecutive podium finish at Daytona Supercrossautomobilsport.com
- DaytonaRacer X Online
- Eli Tomac Soars To Fifth Daytona Supercross VictorySPEED SPORT
- 2021 Daytona Supercross ResultsCycle News
- All Results: DaytonaMX Vice
- 2021 SUPERCROSS STANDINGS AFTER DAYTONADirt Bike Magazine
- Daytona SX: AMA Supercross Round 9 Live Stream for FREE Saturday's Race Time, ScheduleProject Spurs
