Sorry, grandma.

Atlanta United may take on its biggest rival Orlando City with a goalkeeper who is so unfailingly polite that he apologized to his grandmother that he didn’t get a chance to tell her that he was going to play in Wednesday’s game against Sporting KC.

Paul Christensen may not be as intimidating in goal as the hulking Brad Guzan, but his Atlanta United teammates say that he has their full support if he is called up on to start on Sunday against Orlando City, which is riding a six-game winning streak.

“We all trust Paul (Christensen) and know that he’s capable,” Atlanta United midfielder Jeff Larentowicz said. “Obviously, today is the jumping off point for him. The team will move on and do what it can. Obviously, it’s a big game. It’s a team that’s hot and we’re going to go into their place, and we’re going to go and try to win.”

Christensen didn't get a chance to tell his grandmother that he was playing because no one thought that he would be in the 2-0 loss to Sporting KC on Wednesday. The team's fourth-string keeper, Christensen came into the game because Guzan received a red card in the 34th minute. Christensen was signed as the emergency backup to Guzan because Alec Kann and Mitch Hildebrandt are both recovering from knee injuries. Hildebrandt has resumed training. Neither his nor Kann's status for Sunday's game has been announced by Atlanta United.

So, as of Thursday, Christensen, a fourth-round pick in this year’s SuperDraft, is Atlanta United’s last line of defense on Sunday against Dom Dwyer, Sacha Kljestan and the rest of Orlando City.

Christensen, 22 and a native of Woodinville, Wash., said he’ll be ready for whatever manager Gerardo Martino decides. Training during the week against Josef Martinez, Miguel Almiron and Hector Villalba, and with Guzan, Kann and Hildebrandt, helps, he said.

“It’s like any other week of practice, it’s getting ready to play games,” Christensen said. “Treating it the same way. Taking everything one save at a time. Trying to be better one save at a time. If I need to be ready to play the game, play the game. If it’s on the bench, on the bench. If it’s not there, it’s not there. Just kind of getting ready and help the team.”

Christensen handled the scrum of reporters following Wednesday’s loss as well as he made his first save, a rocket from Johnny Russell that hit the Adidas logo on his aqua blue jersey in the first minutes of the second half.

He said he prepared during the week as if he was going to start and not Guzan, a veteran of the English Premier League. So, when referee Mark Geiger pulled out the red card following Guzan’s tackle of Khiry Shelton, Christensen was thrust into the spotlight.

As he walked onto the field, Guzan stopped him, raised a gloved hand, and gave him some advice.

“I told him to enjoy the moment,” Guzan said. “We’ve all been there. We’ve all made our debuts at some point in our careers. For him, it was a proud moment to make his professional debut with the first team. I told him to enjoy the moment and take it all in.”

There’s was also shop talk: Guzan told Christensen not to get too close to his near post on crosses.

Christensen didn’t have time to be nervous in the first few seconds of his MLS debut because the foul on Guzan resulted in a free kick by Graham Zusi. The shot sailed wide, which is a good thing because Christensen looked rooted to his spot, which was nowhere near the shot’s intended destination.

Christensen settled down to make the save on Russell’s shot.

There wasn’t much Christensen could have done to stop Daniel Salloi’s goal, a curling shot from the left that bounced into the goal’s lower right corner.

Christensen said he was most nervous when the ball was at the other end of the field. Those were the moments that gave him time to replay moments.

It’s not common for players picked in the third and fourth rounds of the SuperDraft to stick with MLS teams. Christensen, selected with the 70th pick after a standout career at Portland, said he believes that he been able to survive these first few months in MLS because of his attitude.

“Mistakes will happen and you work hard and work through them,” he said. “Try to get better every day and each time getting on the field my goal is to get a little bit better than the day before.”

Christensen was the first player to be interviewed after the game. It happened so quickly that he hadn’t had time to check his phone for messages.

He said he was sure that his father, Todd, watched the game at work, and likely texted his mother, Cindy, to tell her that he was playing. He hoped his twin brother, Ryan, who wrestles at Wisconsin, and younger brother, Drew, also watched. He said he was also sure his grandmother, who he said recently figured out ESPN-plus so that she could watch games, logged on.

“She’ll be upset because I didn’t tell her I was playing,” he said with a smile. “Grandma, it’s not my fault.”

The whole Christensen family may get another chance on Sunday.