LAKE BUENA VISTA, Fla. (AP) — Youness Mokhtar’s goal in the 18th minute gave the Columbus Crew a 1-0 victory over Atlanta United on Tuesday night in the MLS is Back tournament.

The Crew clinched the top spot in Group E and are the first team in the World Cup-style tournament to win all three of their group matches and not surrender a goal.

Columbus opened tournament play with a 4-0 victory over Cincinnati FC and followed that up with a 2-0 win over the New York Red Bulls.

Columbus will face either Real Salt Lake, Sporting KC or Minnesota United on July 28 in the round of 16.

Atlanta, which won the league two years ago and advanced to the Eastern Conference final last season, lost all three of their matches 1-0. They are the only squad in the 24-team tournament that didn’t score a goal.

It is the first time in Atlanta United’s 3-year history they have been shutout in three straight games. They have not scored in 305 minutes of regulation time in MLS games.

“There’s no magic answer. We have to have some real conversations because this isn’t something that just happens. Three games, six halves and we showed up for the last half,” Atlanta goalkeeper Brad Guzan said.

“The second half was better but nearly good enough for what we stand for. We have to get back to work because this is not even close to being good enough.”

Milton Valenzuela set up Mokhtar’s goal with a pass from the left side of the box to the center. He got off a shot despite being surrounded by three Atlanta defenders.

Miles Robinson appeared to deflect the shot with his foot as goalkeeper Brad Guzan mistimed his dive and it went into the net.

It is the midfielder’s second goal of the season and the tournament. He went off in the 44th minute after being injured. Columbus coach Caleb Porter said Mokhtar had a muscle strain in his right leg and would be limited for the next game.

Atlanta United had two good scoring chances in the final 5 minutes but could not convert.

Gonzalo Martínez’s free-kick from just outside the box went wide right in the 88th minute. A minute later, Anton Walkes’ shot from the left side of the box couldn’t find the far corner.

Columbus goalkeeper Andrew Tarbell had a clean sheet in his first Crew start. Tarbell was acquired in a trade with San Jose before the season started.

Atlanta United wore armbands honoring longtime congressman and civil rights hero John Lewis, who died Friday at age 80 of pancreatic cancer. The black armbands had the letters “J.L” written in white.