Al Horford sat out Friday night’s game against the Celtics with a stomach illness that affected the Hawks center for two days.

It was only the fourth game this season Horford has missed. Coincidentally, he missed an early-season game on the West Coast with a stomach illness that hit several of the Hawks.

Horford attended, but did not participate in, the morning shootaround. According to coach Larry Drew, Horford went to the TD Garden only to get out of his hotel room after spending all day Thursday in bed with the illness.

Horford stayed behind at the team hotel for much of Friday’s game before arriving at the arena for the postgame flight to Atlanta.

Horford will have to wait to try to extend his double-figures scoring streak. He has accomplished the feat in 31 consecutive games. It’s the second longest streak of his career behind 33 consecutive in 2009-10.

Harris available: Devin Harris, who missed the previous two games with a sore left foot, was available Friday after he went through pregame warm-up without pain. The guard took part in the morning shootaround, but wanted to test his foot before the game before making a final decision.

Harris said he had experienced pain in his foot, something that has bothered him much of the season, before re-injuring it Sunday against the Bucks. Before the injury, the Hawks expected to rest Harris for some of the current stretch of five games in seven days.

“We really want to keep a close eye on him and monitor him these last 10 games,” Drew said. “I just feel it’s more important to have him in the postseason than these remaining ballgames. The last thing we want is to have a setback.”

Johnson starts: Without Horford, the Hawks started a lineup that included Ivan Johnson at power forward and Johan Petro at center. It was the third start of the season for Johnson, who entered the game shooting .714 (10-of-14) over the previous three games.

Jeff Teague, Josh Smith and DeShawn Stevenson rounded out the starting lineup, the 26th different unit used by the Hawks this season.

Mack made his case: Shelvin Mack said he is happy for the chance to finish the season with the Hawks. The team signed the guard Tuesday for the remainder of the season after he completed two 10-day contracts.

“I think I did a great job of taking advantage of the opportunities when given the chance,” Mack said. “It’s a great situation. I think every team wants to go into the playoffs with at least three point guards. You always have to stay ready.”

Mack had appeared in 10 games with the Hawks, including three consecutive, and averaged 2.6 points and 1.4 assists.