Former Celtics great Paul Pierce was so confident in his team in Game 2 against the Knicks, he said he would walk to work barefoot “in my robe” if they lost for a second straight game in the second-round series.

“If the Celtics lose Game 2 at home, I promise you, I am walking here tomorrow,” he declared on an FS1 show Wednesday. “I guarantee this one. Put the house on this game.”

That didn’t turn out so great. The Celtics blew a 20-point lead in Game 2, as they did in Game 1, and lost 91-90.

Pierce appeared to honor his vow Thursday, saying he set out before the sun rose for what he said was a 20.2-mile commute to work in the Los Angeles area. He posted updates on Instagram Live. It was unclear whether he was actually barefoot, but bath-robed? Yes.

“All right, time for me to get to steppin’,” he said after 5 a.m. Pacific time, calling himself a “man of my word.”

“I cant believe the Celtics got me out here like this dog,” he said in a later update. “I’m really walking out here like this.”

A little before 9 a.m., Pierce posted another Live of a couple hecklers on the sidewalk.

“You lost that bet, huh?” one of them said.

Pierce took it all in stride, having some fun with them. He said he was about halfway at that point.

A FIRE ALARM was triggered at TD Garden in the aftermath of the Knicks’ victory over the Celtics in Game 2, causing a brief evacuation.

TD Garden officials released a statement late Wednesday saying that an alarm was tripped and that no one was injured. The cause of the alarm is under investigation, the statement said.

Alarms began blaring while New York’s Jalen Brunson and Josh Hart were still at the podium concluding a post game interview. Boston’s Jaylen Brown had just completed his interview session in a separate room when officials directed members of the media toward the exits.

Due to the evacuation, Jayson Tatum’s planned interview session was canceled.

TICKET DEMAND IS so great for Saturday’s Game 3 between the Celtics and Knicks that the average paid ticket price on the resale market approached $2,000.

The average was $1,956 for Game 3 and $1,716 for Game 4, both at Madison Square Garden, according to ticketing technology company Victory Live, which analyzes transactions, not listings, on the secondary market.

The cheapest ticket for Game 3 was $626 on StubHub; for Game 4 it was $613 on Vivid Seats.

The Knicks have become the most exciting story in the playoffs, having erased 20-point deficits to beat the defending champion Celtics in the first two games of the best-of-seven Eastern Conference semifinals.

The Knicks, eliminated in the conference semifinals the last two years, would reach the Eastern finals for the first time since 2000 if they win two more games against the Celtics.

Ticket prices for Knicks home games have surged steadily each day leading into Games 3 and 4. The average resale price last Friday was $767 for Game 3 and $545 for Game 4.