Mladin, the winner of the opening three rounds, looked to have the race in the bag as he led by 7.1 seconds with eight laps to go. But things went wrong and the Australian appeared to have clutch troubles that put him out of the race.
That left a great battle to the finish with Hodgson, Spies and Yoshimura Suzuki's Aaron Yates going to the bitter end.
With one lap to go, Hodgson led by a fraction, but it all went wrong on the entrance to turn three, the Brit running wide and allowing both Suzukis to go underneath him and Spies won by just .666 of a second.
The win puts Spies into the championship points lead with 123 points to Hodgson's 120. Mladin is third with 115 points, one clear of Yates.
Spies said, "This is one of my stronger tracks and I knew my first shot at a win would be here. I also know I'm going to get better as the season goes on, so hopefully I can keep getting better at every track we go to. Just the way things worked out, it was kind of a weird win, but it was still a win and I'll take it. I'm really happy."
Spies was followed to the chequered flag by his Suzuki team mate Aaron Yates, who picked up his second Superbike podium finish of '05.
Five-time Superbike champ Mladin looked like a good bet to pick up his fourth consecutive win, but the determined rider was forced to drop out of the lead deep into the race after encountering mechanical problems. Despite the Australian's misfortune, his team mates proved they were more than capable of picking up the slack.
Second-placed Yates said: "We were pushing hard and we had a good race going -- I'm sure everybody enjoyed it. It's great for Suzuki to be one-two."
Suzuki-mounted riders filled out half of the top ten: In addition to winner Spies and runner-up Yates, Jordan Motorsports' Steve Rapp, Mat Mladin Motorsports' Marty Craggill, and Team M4 EMGO Suzuki's Vincent Haskovec finished eighth, ninth, and tenth, respectively.
Haskovec also earned a trophy for Suzuki on the day by finishing third in the 60k Formula Xtreme final aboard his powerful GSX-R600. It was the Czech Republic native's second straight podium finish in the class.
MPT Racing's Danny Eslick and EMGO-backed Chris "Opie" Caylor joined Haskovec near the top of the results sheet. Eslick finished fourth, while Caylor came home sixth.
Superbike Results:
1. Ben Spies (Suzuki)
2. Aaron Yates (Suzuki)
3. Neil Hodgson (Ducati)
4. Miguel Duhamel (Honda)
5. Eric Bostrom (Ducati)
6. Jake Zemke (Honda)
7. Josh Hayes (Kawasaki)
8. Steve Rapp (Suzuki)
9. Marty Craggill (Suzuki)
10. Vincent Haskovec (Suzuki)
Source: Team Suzuki Press Office