Gaines has started every game for a defense that hasn't allowed a touchdown the last three games. He is the only rookie cornerback in the NFL to start every game.
''A pleasant surprise? No, I wouldn't say that,'' coach Jeff Fisher said Wednesday. ''He took advantage of an opportunity and he's not batted an eye since.
''If there's any element of surprise it would be his ability to jump inside and play the nickel spot as well as he has.''
The Rams (6-8) had consecutive shutouts against the Raiders and Redskins, outscoring them a combined 76-0, before surrendering four field goals in last week's 12-6 loss to Arizona. Another newcomer, first-rounder Aaron Donald, leads rookies with eight sacks and has a five-game sacks streak entering this week's game against the Giants.
''It's not just their front seven,'' Giants quarterback Eli Manning said. ''Their defensive backs are playing well and are aggressive.''
Gaines opened the year at left cornerback in place of injured Trumaine Johnson, has spelled Janoris Jenkins on the right side, and has served as the third cornerback when the team opens in a nickel alignment.
''I played nickel my senior year at Missouri, so that helped me a little bit, and playing a lot of man-to-man coverage at Missouri helped me, too,'' Gaines said.
''A lot of things we did there, we do here.''
Gaines led the Rams with 13 tackles, 10 solo, last week against the Cardinals. He's a hard hitter beyond his 5-foot-10, 190-pound frame, upending a handful of Arizona players with clean, low-body hits.
''I hope he feels it more than I do,'' Gaines said. ''I don't most of the time.''
Gaines has 100 tackles on the year, fourth on the team, to go with two interceptions and 13 pass breakups. Though Jenkins usually covers the opposition's top wide receiver, Gaines will no doubt get a taste of Giants rookie sensation Odell Beckham Jr.
''You can't defend that one catch, you know which one I'm talking about,'' Gaines said. ''Just defending him any way we can, playing great defense.''
Gaines projects confidence at the prospect of defending Manning, too.
''Definitely a great quarterback,'' Gaines said. ''We definitely see some things we might be able to take advantage of in that offense. We've got to have a great game plan.''
Gaines was an All-SEC first-team pick at Missouri, where he finished his career with 37 consecutive starts and racked up 244 tackles, three forced fumbles, 31 pass deflections and eight interceptions.
Lack of size might have held him back a few rounds in the NFL draft. It was a long wait before the Rams took him 188th overall and gave Gaines, of Independence, Missouri, a chance to stay close to home.
Gaines' bid to make the team was somewhat overshadowed for several months by the presence of seventh-rounder Michael Sam, the first openly gay player drafted by an NFL team. Quietly, Gaines carved out a niche, although he had no idea there would be this much playing time right away.
''I don't think anybody did,'' he said. ''I definitely didn't put it past myself. I know I can play this game and it was just getting a chance, getting a shot. It's all great timing for me.''
NOTES: C Scott Wells (coach's decision) was the lone player not practicing while nursing an elbow injury that often has sidelined him early in the week. Fisher said G Davin Joseph would likely sit Thursday, another coach's decision designed to keep the line intact till the finish of the season. ... DE Chris Long practiced midweek for the first time since he returned from ankle surgery three weeks ago.
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