Game 5 was ugly, but the Celtics are sitting pretty against the Heat

Jayson Tatum (22 points) came within one assist of a triple-double in Game 5.Matthew J Lee/Globe staff

MIAMI — It took five smashmouth games and a lot of time in the training room, but it feels like the Celtics finally wore down the top-seeded Miami Heat.

After staggering through a brutal two quarters (both teams), the Celtics came back from a 5-point halftime deficit, tightening the screws on defense and outscoring Miami, 32-16, in the third quarter for a 93-80 Game 5 victory in the Eastern Conference finals. Game 6 is Friday night on Causeway Street and the Celts are one victory from making it to the NBA Finals for the 22nd time in franchise history.

“It’s great to be up, 3-2 and to have it at home is an advantage,’’ said Boston’s rookie coach, Ime Udoka. “ . . . Our defense, we stayed steady. Tonight we kept our composure and relied on our defense. That travels well with us.’’

Ime Udoka directs the action during the third quarter of Wednesday's contest.Matthew J Lee/Globe staff

A couple of weeks ago former NBA sharpshooter-turned-bloviator, JJ Redick tried to diminish NBA competition from the 1950s and ‘60s, claiming Bob Cousy and Co. played against a bunch of “plumbers and firemen.’’

Trust me when I tell you that the guys from Plumbers and Gasfitters US Local 12, and Oak Square’s Engine No. 51 would have played better ball than what we saw from the Celtics and Heat much of Wednesday at FTX Arena. If Chuck Wepner fought Hurricane Peter McNeeley, it probably would have looked something like this.

But the Celtics and their fans don’t care about style points at this hour. On the strength of their Belichickian defense, the Sons of Udoka — 39-12 since Jan. 23 — are on the threshold of the Finals. They vaporized the Heat, forcing Miami to shoot 31.9 percent (30 of 94, 7 of 45 on threes). Jimmy Butler made 4 of 18 shots. Miami’s starting guards (Kyle Lowry and Max Strus) went 0 for 15 from the floor. It was like watching Philip Seymour Hoffman shooting hoops in “Along Came Polly,” screaming “Let it rain!’’ as he clangs one shot after another.

It’s only been five games, but clearly the Heat are spent. If the Celtics don’t beat these guys Friday night at home, they won’t deserve to go to the Finals.

Udoka had all of his players Wednesday, no small advantage in a smashmouth series festooned with attrition. Marcus Smart (ankle) and Robert Williams (knee) were in Boston’s starting lineup, while the Heat were forced to go without NBA Sixth Man of the Year Tyler Herro (groin). It was quickly clear that Butler (knee inflammation) and Lowry (hamstring) are cooked.

This was the first game of the series in which neither team took a 20-point first-half lead. We even had four lead changes, which is a lot for a series that had zero lead changes in Games 1 and 2.

We figured the Heat had to be better than they were in Game 4 in Boston when they missed their first 14 shots, trailed, 18-1, and 29-11 at the end of one quarter. Miami’s starting lineup scored an aggregate 18 points in that game, which has not been done in the last 52 years, and quite possibly never.

The Heat were not better. They are cooked.

Miami missed its first six shots of Game 5, going scoreless for the first 3½ minutes before Butler broke the lid.

The Celtics were no better in the first half. Jaylen Brown had four turnovers in the first quarter and shot 2 of 7 in the first half. Jayson Tatum (more shoulder/arm problems) made only 1 of 9 shots, scoring 4 in the half. Smart did not make a basket in the first two quarters.

Jaylen Brown overcame a slow start to power Boston down the stretch Wednesday night in Miami.Matthew J Lee/Globe staff

With Grant Williams starting in place of Rob Williams in the third, Boston scored the first 8 points to regain the lead. Late in the third, Rob Williams made a huge block on Victor Oladipo, one of seven Celtic blocks.

The Celtics ran away with it at the end of the third and the beginning of the fourth, leading by as much as 23. Brown finished with 25, Tatum with 22, and Al Horford had 16.

But it’s not shooting and scoring that’s got the Celtics on the brink of the Finals.

It’s defense . . . in the spirit of Bill Russell, K.C. Jones, Satch Sanders, and Dennis Johnson — who played in a bunch of Finals and won a bunch of championships for the Boston Celtics.