PITTSBURGH — The seeds for a rivalry between Curtis Brown and Cortez Allen were planted early.

Selected one round apart by the Pittsburgh Steelers in the 2011 NFL Draft, the two cornerbacks found themselves fighting for playing time – and a roster spot – on a defense that isn’t exactly the easiest to learn.

Brown, a third-round pick, played at Texas. Allen, who went a round later, played at The Citadel, far away from the bright lights of big-time college football.

Coach Mike Tomlin admits he “pitted” the two youngsters against one another much the way he did with wide receivers Antonio Brown and Emmanuel Sanders, separated by 113 picks in the 2010 draft.

The ploy worked, kind of. While Brown and Allen freely admit they’re better off for having to compete with the other, there is no blood feud, no looking over each other’s shoulder to see what the other is doing.

“He’s probably my closest friend on the team,” Allen said.

The fact the Steelers initially rated Brown a little higher never comes up, perhaps because both players know it’s irrelevant. They were selected to be teammates, though that hasn’t stopped Tomlin from using the “two dogs, one bone” metaphor to try to help them bring out the best in each other.

While they have, that competitiveness doesn’t carry over off the field.

“We chill every day,” Brown said. “We hang out together in the offseason. We’re in it for the long run.”

One that’s starting a little sooner than planned.

Allen and Brown will see extensive playing time on Sunday when the Steelers (7-5) face San Diego (4-8) as Pittsburgh takes the field without injured veteran cornerback Ike Taylor for the first time in eight years.

Taylor is out at least two weeks with a fractured right ankle, leaving Pittsburgh’s top-ranked pass defense very young and more than a little fired up.

“I take the approach that you should always be prepared,” Allen said. “I was ready for this and I feel like the coaching staff and my teammates are confident in me to get the job done.”

The bigger, bulkier Allen – who at 6-foot-1 and 196 pounds is an inch taller and 11 pounds heavier than Brown – will start at cornerback then slide into his usual nickel spot in passing situations while Brown replaces him on the outside.

It’s a setup both feel plays to their strengths. Brown feels more comfortable going one-on-one on the outside, where quickness and instincts can overcome mistakes, while Allen’s cerebral approach makes him a perfect fit for the sometimes complex coverage assignments.

“I’m just trying to make a name for myself at corner,” Brown said.

He’s already on his way. Brown didn’t have time to get nervous last Sunday when Taylor went out in the first quarter. Suddenly he found himself thrust into a critical spot in the most important game of the season.

Don’t think the Ravens didn’t notice, targeting Brown twice on third downs shortly after he came onto the field. Both plays ended up with incompletions in the Steelers’ 23-20 win.

“They cooled off after awhile,” Brown said. “They tried me the first two third downs and they weren’t successful ... They didn’t throw much at me after that.”

Allen’s start proved rockier. Baltimore wide receiver Anquan Boldin lit him up several times in the first half as the Ravens moved the ball with relative ease as Baltimore eased to a 13-6 lead.

Getting picked on didn’t tighten Allen up. If anything, it helped him relax.

“The new guy, yeah, (teams) try to go at him,” Allen said. “It’s something you have to ready for. Every down you play, you have to play like it’s coming to you. I was ready for it and expecting it and I accept that challenge.”

So does fourth-year cornerback Keenan Lewis, who suddenly finds himself the elder statesman. Lewis has provided a sounding board for both Allen and Brown, maybe it’s because he’s used to being considered the weaker link with Taylor on the other side of the field.

There’s a reason Lewis is tied for the NFL lead in passes defensed: Teams would prefer to throw at him than Taylor. He endured much the same way the kids lining up next to him will have to endure on Sunday against one of the league’s biggest receiving corps.

Then again, being relatively anonymous isn’t exactly a bad thing. When asked what he knew about Allen and Brown, San Diego quarterback Philip Rivers just laughed.

“Not a ton obviously,” Rivers said. “I know it’s a confident group of guys that stepped up in the game and played there in Baltimore and won.”

Something the two young cornerbacks know is the standard in Pittsburgh no matter who is on the field. There will be times when it’s just one of them out there. They’re fine with it, knowing when the time comes, they have each other’s back.

“The ‘two dogs, one bone thing,’ that’s a Coach T thing,” Brown said. “We’re just working every day.”