TORONTO – Chan Gailey described his first win as Buffalo Bills head coach as an important step for his team.

If that’s the case, it was a big and powerful step forward provided by rookie running back C.J. Spiller.

It took four plays into the Bills’ opening drive for the first-round draft pick to begin delivering on his dynamic billing by scoring on a 31-yard run and sparking a 34-21 win over the Colts in a preseason game Thursday.

It came in Spiller’s debut as starter in place of veterans Fred Jackson and Marshawn Lynch, who were both injured a week earlier.

The only disappointment was the small crowd of 39,583 – more than 14,000 below capacity – that turned out for the fourth of an eight-game, five-year series the Bills are playing in Toronto.

“I think you can see tonight why we drafted C.J.,” Gailey said of the player selected ninth overall out of Clemson. “Obviously, running the ball is what he does best. And he made an unbelievable run on that touchdown.”

Peyton Manning and the high-powered Colts (0-2) didn’t disappoint in what proved to be a wide-open and entertaining first half. After opening with a three-and-out, Manning engineered two scoring drives on the next four series, including a perfectly placed 21-yard touchdown pass over the middle to tight end Jacob Tamme on a third-and-9. Joseph Addai also scored on a 17-yard run.

Manning went 8 for 15 for 91 yards, with an interception that was returned 78 yards for a touchdown by Terrence McGee. Manning was trying to squeeze a pass into Anthony Gonzalez when defender Drayton Florence got his hand in, deflecting the ball directly to McGee, who ran it back untouched up the left sideline.

“We’ve still got some work to do. That’s kind of what preseason is for,” said Manning, the NFL MVP last season. “You want everything to go perfect while you’re in there. That’s not always the case, but I think you’ve got to have those kind of expectations.”

Backup quarterback Curtis Painter had a solid showing after he was booed off the field while throwing three interceptions in a 37-17 loss to San Francisco on Sunday. On his second series, Painter drove the Colts 81 yards on two plays for a touchdown. After hitting Taj Smith for a 38-yard pass, Painter went back to Smith for a 43-yard touchdown pass.

“Curtis Painter certainly had a better evening,” Colts coach Jim Caldwell said. “I think he played well, threw the ball well.”

The big loser this week has been Rogers Communication, which has been under heavy criticism in the Toronto media this week for paying the Bills $78 million two years ago for the right to play host for the series, which runs through 2012.

Neither of the first three games of the series fully sold out the 54,000-seat facility.

The crowd that did show proved lively, but it’s unclear how many paid full price for their tickets, which ranged from $75 to $275. Though there were numerous fans wearing Colts jerseys, the Bills did have the larger contingent, and attracted several loud and extended cheers throughout the first half.

“I thought it was good. I didn’t know what to expect,” Manning said. “I thought the fans, it seemed like they were all having a good time up there.”