Apparently that limit was "all of them," because he played 41 of a possible 48 minutes and the Hawks needed every one, right down to the final second, to beat the Boston Celtics 87-86 in Game 5 and stay alive in their best-of-seven series. Game 6 is Thursday in Boston.
"I did not expect to play that many at all," said Horford, who played in his second game after missing 55 during the regular season with a chest injury. "We had an agreement that it was going to be between 15 and 25. But it was an elimination game and I felt good. I was tired a bit, but I kept pushing through it."
He kept playing better too, finding another gear in the second half after looking winded just a few minutes in to the game. Seventeen of his game-high 19 points came after the break. In fact, Horford had enough left in the tank to make four of his five shots in the fourth quarter, including a difficult baseline hook shot that provided Atlanta's final points with 1:34 to go.
And he felt good enough, at the end, to completely bottle up one of the league's fastest players. After Atlanta threw away an inbound pass with 10 seconds left, Rajon Rondo streaked up court looking to give Boston a series-clinching basket. But Horford switched out on Rondo after a Kevin Garnett screen, crowded him at the 3-point line and wouldn't let him past. Rondo made a foray toward the baseline that failed, dribbled back outside and ultimately lost the ball as the clock expired.
"He was actually shooting the ball pretty well, hitting jumpers," Horford said, "and I didn't want to lose the series in that way. So my whole thing was to force him to pass the ball and crowd him as much as I could."
"Al makes a big difference," Rondo said. "He can guard anybody on the court."
Horford finished with 11 rebounds, and his return -- in his first start in nearly four months -- provides some renewed intrigue to the Ugly Bracket of the Eastern Conference playoffs, in which the Chicago Bulls provided similar thrills by beating the Philadelphia 76ers in a 77-69 slugfest to extend their series. The winners will meet in another best-of-seven grind for a place in the conference finals.
Horford's return was palpable at both ends, but especially offensively. Atlanta had been killing a power play on offense with Boston ignoring the Hawks' centers, but Horford made them pay. Joe Johnson said Boston's strategy of crowding him didn't change, but the result did; Horford was constantly open and he either scored on his own, found the open man (three assists), or facilitated a pass to open up a previously clogged offense.
The telltale sign: Open corner 3-pointers. They'd been as rare as chowder in these parts, but Atlanta got several Tuesday night and converted 7-of-16 from distance. Marvin Williams, instated as a starter to guard Boston's Paul Pierce, made three of them, tripling his total from the first four games.
It still wasn't the 2005 Phoenix Suns, but 87 points is enough to win games in this series. Atlanta hadn't scored more than 84 in any of the first four games.
With Horford back and another quality big man, Zaza Pachulia, possibly joining him if there's a seventh game, the question mark on this series returns. We know the Celtics are better than those Hawks, the ones without Horford. But are they better than these Hawks?
Probably, but a shred of doubt now remains. In all likelihood, it's a brief reprieve -- teams trailing 3-2 and going on the road for Game 6 don't have a glorious history, but the Celtics do. Atlanta is only 2-11 in Boston in the Garnett era, although the Hawks took the Celtics to OT in Boston twice this season -- once in the regular season and again in Game 3.
While Horford provided a reminder of how much better he makes the Hawks, there's no guarantee that continues. He hasn't played in four months and may not necessarily have this kind of effort in him in 48 hours.
However, Horford's return isn't the only factor. The Battle of Wounded Knee now appears to favor Josh Smith over Pierce, who was moving gingerly for much of the second half, took an eight-minute break on the bench, and airballed a potential game-winner on the Celtics' penultimate possession.
And it's encouraging that the Hawks survived bad games from their two best players while sans Horford. Joe Johnson was 6-of-17 with four turnovers, including a brutal one on a mystifying play at the end of the third quarter that led to an easy Boston lay-up, capping a 10-0 run that rallied the Celtics within two to start the fourth.
Smith had an even worse turnover, throwing away an inbound pass with 10 seconds left to give Boston its final chance. He finished 6-of-16 with four turnovers and a missed dunk.
Finally, the Celtics may not receive this much generosity from the opposing coaching staff. Atlanta kept beating the iso-Joe horse in the fourth quarter to little effect and bizarrely played Willie Green instead of Kirk Hinrich in the second half; Green was -11 in seven minutes and only a defensive board saved him from Club Trillion.
Nonetheless, winning in Boston is a very different animal before winning in front of the home crowd, even if the Hawks probably saw nearly as many Celtics fans on the night as they will in TD Garden on Thursday.
Thanks to Horford, they'll get to try. Now it's off to Boston, to see if he makes enough of a difference to swing the series back in Atlanta's favor.