No matter. The Hawks still found a way in the final minutes to pull out another win.
Josh Smith had 22 points and 11 rebounds as the Hawks (5-0) remained the only unbeaten team in the Eastern Conference.
"We haven't yet played our best, but we're still winning," said Johnson, who made only 5-of-15 shots for 14 points and had a game-high eight assists.
"We're starting to grow. It's a beautiful thing to see."
Ben Gordon had 22 points but it wasn't enough for Detroit.
The Pistons are 0-5 for the first time since the 1980-81 season, when they started 0-7. They won their fifth game after starting 0-4 in 1999-2000.
"Nobody envisioned it but obviously it's something we're going to deal with now and try to figure out (how) to go forward with this," forward Tayshaun Prince said.
Prince, who had 17 points, hit a 3-pointer to give Detroit an 81-76 lead. The Hawks then took over with the closing run over the final 6:13.
"I thought our guys played their hearts out," Pistons coach John Kuester said. "Coming down the stretch, again, we've just got to make sure we're efficient."
Charlie Villanueva had 14 points for Detroit.
The Pistons used their 17-3 advantage in offensive rebounds to take a 16-6 lead in second-chance points. The Hawks averaged 44 rebounds in their first four wins, but they were outrebounded 38-35 by the Pistons.
"We were a little careless in that area," said Horford, who had eight rebounds as his streak of three straight double-doubles ended. "It almost cost us."
The Hawks led 70-66 entering the final quarter. Gordon opened the period with consecutive baskets to start a 10-2 run that gave the Pistons a 76-72 lead.
The most important minutes to close the game belonged to Atlanta.
"If there's one thing about this team that I'm starting to see, it's more and more maturity," said Hawks coach Larry Drew. "We aren't panicking, especially down the stretch."
The Hawks were without Crawford, their top sub who suffered a right turf toe injury in Tuesday night's win at Cleveland. Crawford, chosen as the NBA's Sixth Man of the Year last season, is averaging 15.8 points.
Crawford said after the game he hopes to play Friday at Minnesota.
The Hawks already were without another top backup, guard Maurice Evans, who missed his fourth straight game with a right knee injury. Then Williams left the game with 6:34 remaining after landing hard on his right knee in a battle with Greg Monroe for a loose ball.
"I just banged it," Williams said. "We'll see how it feels in the morning."
Hawks rookie Jordan Crawford, who played only two minutes over the first four games, moved into a more prominent role and scored his first career points with a jumper late in the first quarter. It was his only basket of the game.
The Pistons took advantage of Gordon's matchup with Mike Bibby. Gordon opened the game with a reverse layup and continued to attack Bibby, scoring 11 of the Pistons' first 16 points.
- The Pistons made only 3-of-17 3-point shots. Villanueva was 0 for 5.
- Pistons G Richard Hamilton (sore right foot) missed his second straight game. F Tracy McGrady played after he was listed as questionable with a sore left knee.
- The Hawks shot 60 percent from the field in the first half and still trailed 48-44. They shot 53.7 percent for the game.