INDIANAPOLIS – It was the running back not many expected to be starting in Week One of the preseason.

When the Colts first-team offense trotted onto the field Saturday night in Buffalo, Frank Gore was in street clothes.

That was expected.

The man filling his starting spot was a surprise.

Josh Ferguson, an undrafted free agent out of Illinois, was the starting running back, ahead of veterans Robert Turbin and Jordan Todman.

Even though Ferguson and the run game could not get things going (Ferguson had eight carries for three yards), it's clear the undrafted jitterbug has already made an impression on this staff.

Here's a look at some other names that might have swayed the Colts' coaching staff on Saturday, a game in which the young guys played their most this preseason, until Week Four against Cincinnati:

• WR-Tevaun Smith:The undrafted receiver from Iowa led the Colts with six targets on Saturday (three catches for 34 yards). The 6-2, 205-pound Smith also drew a late first half pass interference penalty that led to a field goal. With a handful of undrafted receivers, a couple are going to emerge and challenge for a roster spot to close out the preseason.

• WR-Chester Rogers:If Rogers does go on to make the Colts, a broken tackle in Buffalo will certainly be one of the reasons why. The 57-yard game-winning touchdown from Rogers came thanks to his individual effort of muscling through a would-be tackler before turning up field. Like Smith, Rogers would do wonders for himself if he can prove his worth on special teams, while still making plays at receiver.

• ILB-Edwin Jackson:Listed as a backup inside linebacker, Jackson backed up his strong Training Camp against Buffalo. Jackson led the Colts with eight tackles on Saturday night.

• ILB-Antonio Morrison:Before Saturday's game, Chuck Pagano made it clear Morrison has already stood out: "That 44 is a football player. That's what they are supposed to look like. That's what they are supposed to sound like. That's how they are supposed to run around, hit." Morrison, a fourth-round pick this year, had two tackles on Saturday. Morrison and (Edwin) Jackson are two young inside guys the Colts have behind the likes of D'Qwell Jackson, Nate Irving and Sio Moore.

• OLB-Curt Maggitt:We needed to see Maggitt in a game setting and he delivered. The undrafted free agent out of Tennessee had three tackles for loss on Saturday night. Nearly 11 months removed from a hip injury that ended his senior season, Maggitt had a strong NFL debut at a key position for the Colts.

• OLB-Earl Okine:That "stab/spin" move from Okine sure looked like he knew what he was doing at his new position. A third-quarter sack from Okine on Saturday came from his new standup role at outside linebacker. Okine credited Trent Cole for teaching him that move. At 6-5, Okine says he's learned quite a few moves from the veteran edge rushers that weren't in his arsenal last year.