The Buffalo Bills spent more than half of the 2018 NFL season searching for a cornerback to play across the field from Tre'Davious White, who'd stepped into the lineup as a first-round draft choice from LSU in 2017.

The Bills used Vontae Davis, Ryan Lewis and Phillip Gaines before turning to a practice-squad player in the 10th game of the season -- Levi Wallace, an undrafted rookie from Alabama. After his promotion to Buffalo’s active roster, Wallace started the remaining seven games and played all but 11 of the Bills’ defensive snaps in that span.

But that didn't reserve the job for Wallace in 2019.

In free agency this offseason, Buffalo signed Kevin Johnson and E.J. Gaines. Johnson was a first-round draft choice for the Houston Texans in 2015 who missed 29 games in the past three seasons. Gaines was a starter for the Bills in 2017 who left for the Cleveland Browns in free agency but played in only six games last year.

“Competition makes the best out of everyone,” Wallace said. “It’s nothing new. At Alabama, they were five-stars and I was a walk-on. At this point, it’s my story.”

Levi Wallace has been proving doubters wrong his whole career. pic.twitter.com/uA18HzoqXG — Pro Football Focus (@PFF) January 19, 2019

Wallace went from a walk-on to a starter at Alabama, and essentially did the same thing in the NFL last year.

The Bills will wrap up their offseason program this week with mandatory minicamp, which will end the cornerback competition until Buffalo reconvenes for training camp in late July.

“They’ve done a good job, starting with Tre’Davious and the way he’s worked at his craft this offseason,” Bills coach Sean McDermott said about the Bills’ cornerbacks last week. "And then Levi and his growth and story has been well-documented for the last couple of weeks. And he’s earned that. And Kevin and E.J. and the rest of the guys have been in there battling as well.

"What I love about Kevin is that he's gotten his hands on some footballs the last few weeks here and taken the ball away a few times. So his mindset has been impressive just from his mental toughness and his focus at this point. That's been good to see."

Wallace said he's had to match the intensity of the new cornerbacks.

“Those guys come in, and they’re hungry, you know?” Wallace said. “So it just makes me step up my craft and try to master what I do even at a higher level. But it’s been good, and, like I said, the receivers have pushed us as well, with John Brown and … with Rob (Foster) even coming back, you know, it’s been really good to go against those guys, and they make us better.”

Lightning struck in the same place twice for Buffalo last season with Wallace and Foster. Foster also was an undrafted rookie from Alabama who came off the practice squad to earn a starting position.

Foster made the Buffalo regular-season roster coming out of the preseason, but six games into 2018, he had two catches for 30 yards. The Bills released the wide receiver on Oct. 19, then re-signed Foster for their practice squad when he cleared waivers.

After three weeks on the practice squad, Foster rejoined Buffalo's active roster and immediately produced the Bills' first 100-yard receiving game since Oct. 22, 2017. In his first NFL start, Foster caught three passes for 105 yards in a 41-10 victory over the New York Jets on Nov. 11.

In his second game back, Foster caught his first NFL touchdown pass -- a 75-yarder -- in a 24-21 victory over the Jacksonville Jaguars.

After the Bills released their No. 2 and No. 3 receivers, Kelvin Benjamin and Andre Holmes, Foster posted 100-yard outings in consecutive games on Dec. 9 against the Jets and Dec. 16 against the Detroit Lions.

Foster caught 25 passes for 511 yards and three touchdowns in the Bills' final seven games. He led the NFL in yards per catch (for players with at least 25 receptions) at 20.04 in 2018, joined Amari Cooper, JuJu Smith-Schuster and Michael Thomas as the only players since 2015 with at least three 100-yard games as rookies and became the first Buffalo player in 32 years with a 25-yard-or-longer reception in six consecutive games.

“The second year is always different than the first,” McDermott said, "and therein lies the challenge for Levi and Robert, who experienced success in their first season, to come out and reinvent themselves this next year.

"The challenge will be different. There's tape on them out there now. Much like a pitcher in baseball, they're not going to be sneaking up on anyone this season, and so they have to continue to challenge themselves, remain confident but know that their role may be slightly different this season than it was last season."

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Mark Inabinett is a sports reporter for Alabama Media Group. Follow him on Twitter at @AMarkG1.