He made the team in 2015 as the swing tackle and was thrust into the starting role after Kelvin Beachum — now in Jacksonville — tore his anterior cruciate ligament six games into the season.
"Al did a great job last year and he's a guy who's still learning so much," offensive line coach Mike Munchak said of the 27-year-old Villanueva, who appeared in all 16 games.
Villanueva stepped right in, starting the final 10 games.
"Al's got so much upside and the more he plays, he just gets better every time he's out there."
"Everybody makes mistakes, but one mistake can cost you the game Sunday," Villanueva said. "You can play a great game, but if you give up a sack, it's really ugly."
"I'm thankful for the opportunity to at least get to compete."
Munchak believes the competition has brought out the best in both players, as Villanueva and Harris rotate daily with the first-team offense. He's excited to see who ultimately wins the job.
LATROBE, Pa. (AP) — Pittsburgh Steelers lineman Alejandro Villanueva has a chance to compete for one of the most important positions along the offensive line.
"For an undrafted guy like me, this is a best-case scenario, to be able to compete for a starting position coming into my second year," Villanueva said. "Usually the draft or free agency brings in high-caliber players and I feel I can compete with players, but I just can't compete with a salary.
The Steelers signed Villanueva to their practice squad in 2014 after he was cut by Philadelphia as a defensive end. The team moved the 6-foot-9 Villanueva to left tackle as the former undrafted free agent and Army Ranger gained almost 100 pounds to play along the offensive line.
The 6-foot-5, 302-pound Harris has appeared in 110 games,World Baseball Classic Jerseys Outlet, making 70 starts. Harris played for three different teams, including two stints in Denver.
"You want to do it as quick as you can, so the group knows which direction we're headed and they can get used to each other," Munchak said. "I think it has a way of playing itself out where it becomes obvious who's the best fit."

"He was a Super Bowl champion and that brings confidence to your play and the people around you. He's learned a lot over the years and he's a nice addition to our group."
Harris, a nine-year veteran, earned a Super Bowl ring last season, starting all 19 games at left tackle for Peyton Manning,Nike Just Do It Uomo, Brock Osweiler and the Denver Broncos. The 31-year-old Harris signed a two-year contract with the Steelers as an unrestricted free agent in March.
"Ryan has a lot of experience and already knows a lot of the little stuff that Al's learning because he's been in the league and he's been successful," Munchak said. "He's been through the ups and downs of the NFL.
Villanueva, in just his second season, is locked in a tight training camp competition with veteran free agent acquisition Ryan Harris at left tackle, the blind side of Steelers star quarterback Ben Roethlisberger.
Villanueva feels as if he's grown substantially entering his second season. He took an important lesson from his first NFL start at left tackle — a loss at Kansas City — when he allowed a sack against Tamba Hali that clinched the victory for the Chiefs.
NOTES: Roethlisberger,Brandon Finnegan Jersey, running backs Le'Veon Bell and DeAngelo Williams and wide receiver Antonio Brown all will not play Thursday against Philadelphia. ... Bell,David Robinson Jersey, who faces a four-game suspension for violating the league's substance-abuse policy,Cheap Jerseys China, said he doesn't know when his appeal will be heard.
"My perseverance has given me a lot of confidence, almost as much confidence as my Super Bowl ring," Harris said. "I'm just happy to be able to continue to do something I love every day."