OAKLAND, Calif. -- Alex Smith did about all he could reasonably do to get the Kansas City Chiefs a victory Thursday night. He threw for 342 yards and three touchdowns, and the Chiefs led the Oakland Raiders by six points when he left the field for the last time.

But he wasn't out there when the game was ultimately decided. The Raiders drove 85 yards in the final 2 1/2 minutes, the touchdown that gave them a 31-30 victory coming as time had expired.

The feeling was for Smith as helpless as it might sound. The back and forth of the final five plays was extreme. The Raiders lost one TD on a video review and another on a pass interference penalty. The Chiefs lost what would have been two game-ending incomplete passes to holding penalties.

Then came Michael Crabtree's 2-yard touchdown pass from Derek Carr. No penalties, but there was a lengthy video review to determine that it was indeed a touchdown.

"Just watching, just rooting," Smith said. "You're a fan at that point, rooting for our defense. There were so many close plays out there.

"Several times they're thinking [the Chiefs had won]. How could you not? Multiple times you were thinking, we lost it, we won. We lost it, we won it."

Like many of his teammates, Smith was frustrated by some of the officials' calls. Oakland wide receiver Amari Cooper appeared to push Chiefs cornerback Terrance Mitchell on his 38-yard touchdown catch early in the game.

Then the Chiefs were penalized on those back-to-back plays immediately before the winning score.

"I hate seeing all the flags at the end," Smith said. "I think that's the one thing, [that] you want to let your guys play and you don't want the refs involved as much as possible. That second-to-last play, the ball got thrown out of the end zone and they called defensive holding and it's not even close to the play.

"Obviously, flagrant things have to be called. There are rules. You have got to play to the rules, no question. I think there was a bunch of contact all night with balls that went downfield. If you wanted to, you could find a foul on every play."

The ending ruined an otherwise big game from Smith, who until the Chiefs lost their lead appeared only to bolster his already strong case to be NFL MVP. Smith didn't throw an interception, and two of his three touchdown passes went for more than 60 yards.

But Smith's play Thursday night turned out to be something less than the big story.

"There's no time to reflect," Smith said. "You're coming off a loss. You're in the middle of the season. All of that stuff means nothing at this point. That's for after the season."