Among the many concerns from last week’s 4-0 loss at Houston, Atlanta United giving up two goals on corner kicks may be the most worrisome ahead of Sunday’s game against D.C. United at Mercedes-Benz Stadium.

The team conceded seven goals on set pieces in 34 games last season, tied for seventh-most in MLS, according to the league. D.C. United scored five goals off set pieces last season. That total was tied for 15th-most in MLS.

After the Houston game, manager Gerardo Martino said goals allowed on set pieces typically occur because of individual break downs.

Houston’s first goal came when Alberth Elis picked Jeff Larentowicz, which gave Philippe Senderos space to connect with a header. A pick, a play in which one player uses his body to prevent an opposing player from moving in a certain direction, is illegal in soccer.

“We talked a little bit at halftime that they we were trying to set picks,” Michael Parkhurst said. “It’s something that we will have to be ready for.”

When defending corners, Atlanta United typically marks man to man, which invites picks, according to Parkhurst.

“Have to make sure that referees are aware of it, to look for it,” he said. “Also, being able to switch or fight through things. It takes communication in the box. It happens really quick, so you have to be ready for it. Hopefully we will be going forward.”

The second goal came when goalkeeper Brad Guzan, trying to punch away a long corner, instead pushed it back toward the middle of the penalty box, where it was kicked into the goal.

The team hadn’t worked on set pieces as of Wednesday. That discussion was planned to take place later this week.

“It’s just a collective thing,” midfielder Julian Gressel said. “We have to be better. It’s 1v1 matchups. Everyone has their own responsibilities that we have to be prepared to do when it comes to those situations.”