The Falcons’ plan to revamp their offensive line suffered a major setback Tuesday.

Mike Johnson, who was listed as the No. 1 player at right tackle, suffered a dislocated left ankle and fibula fracture during Tuesday’s practice, according to coach Mike Smith.

Johnson is scheduled to have surgery next week.

He was carted off the field after the injury and taken directly to the ambulance. Several longtime observers of Falcons practices couldn’t remember the last time a player went directly from the cart to the ambulance.

Johnson, who was drafted in the third round of the 2010 draft, was attempting to replace the departed Tyson Clabo, who was waived in an offseason move to create salary-cap space for Matt Ryan’s contract.

Clabo, who started 100 games for the Falcons, immediately signed with the Miami Dolphins.

On the first play of the nine-on-seven drill, Ryan handed the ball to running back Steven Jackson. Johnson ended up on the bottom of a pile. Trainers rushed to the aid and shortly thereafter, the cart pulled onto the field. Lamar Holmes, a second-year player from Southern Mississippi, replaced Johnson.

Later, Holmes became winded and threw up when the offense was running an up-tempo drill with 56 seconds left on the clock. He was replaced by Ryan Schraeder, an undrafted rookie free agent from Valdosta State, who’s having a stellar camp.

In addition to replacing Clabo, the Falcons are replacing center Todd McClure and settling on a right guard. Peter Konz, who played in all 18 games and made 12 starts, is set to move to center from right guard.

Garrett Reynolds is the No. 1 right guard. He opened the season as the starting right guard in 2011 and 2012, but was replaced in 2011 and suffered a back injury that required surgery last season.

Johnson played in short-yardage formations and special teams last season. He played 250 snaps overall and 105 of 1,058 (9.9 percent) offensive snaps. Holmes, who had a stress fracture in his foot last season, played only seven snaps from scrimmage.

“The foot injury last year was just kind of something that happened,” Holmes said. “It kind of went both ways. It helped me, and it kind of hurt me.”

Holmes wasn’t ready to stake claim to Johnson’s spot.

With McClure in retirement, left guard Justin Blalock (99 NFL starts) and left tackle Sam Baker (61 starts) are the leaders on the offensive line.

“We’ll try to keep him up and wish him the best,” Blalock said of Johnson.

Holmes spent all of last season working at left tackle, but the Falcons like to train their linemen to play several positions.

“This is the type of business where things of that nature happen, and the next man has to be ready to finish the game,” Blalock said.

Baker has worked with Holmes and Schraeder in the tackle drills. The Falcons also have tackles Terren Jones, an undrafted rookie from Alabama State, and Alex Savoie, an undrafted rookie from McNeese State, in training camp.

Baker knows the group will look to him for leadership.

“It’s really about holding guys accountable and making sure that they know what they are supposed to be doing,” Baker said. “You want to make sure that their head is in the playbook and that they are doing what the coaches are telling us to do.”

Schraeder, 25, is the second-oldest rookie in the undrafted free-agency class behind linebacker Brian Banks (28).

Schraeder, 6-foot-7, 300 pounds, earned All-American honors at Butler Community College and then went to Valdosta State and was an All-American in 2011.

“I’ve been going back and forth,” Schraeder said. “They’ve been working me both sides just to get me comfortable with the offense and see what I can do.”