LeBron James scored 21 points, jamming in a dunk over a defenseless Kevin Garnett in the final two minutes, as the Cleveland Cavaliers beat the Celtics 88-77 in Game 4 on Monday night to tie the best-of-seven series at 2-2.

Still stuck in a shooting slump, James dominated down the stretch and finished with 13 assists -- four in the fourth quarter. The Cavaliers, whose defense has been overlooked, held the Celtics to just 12 points in the final period.

"We took care of home court and turned it into a three-game series," James said.

Boston dropped to 0-5 on the road in these playoffs, a stunning slip for a team that went 31-10 on the road in the regular season.

"It's hard to say. I have no answer for it," Ray Allen said.

During a short visit to Ohio, the Celtics lost their momentum in the series but will now head home, where they went 35-6 before the playoffs started.

Game 5 is Wednesday night, and Game 6 will be back in Cleveland on Friday.

"We're disappointed right now," forward Paul Pierce said. "I had a lot of shots that I usually make, but I'm not going to really dwell on it."

James was just 7-for-20 from the floor, but he did everything else for the Cavs, who are attempting to overcome an 0-2 deficit for the second time in two years.

With the Cavs leading 82-75, James drove past Pierce on a screen near the foul line, head faked past James Posey and then posterized Garnett, the league's defensive player of the year. As Cavaliers fans erupted, a scowling James stormed back on defense.

"I just wanted to be aggressive. I hadn't had a play like that all series," James said.

Although James is shooting only 20-of-78 (26 percent) from the floor, the only numbers the Cavs care about are the pair of 2s that show this series is as tight as possible.

Garnett scored 15 points, but only two in the second half, as Cavs forward Anderson Varejao harassed Boston's All-Star all night. Allen had 15 points and Pierce 13.

James missed his first six shots in the fourth before draining a 3-pointer in front of Boston's bench with 3:17 remaining to give the Cavs a 79-73 lead. After the ball swished through the net, James made an it's-about-time shrug.

After a bucket by Pierce, James dished to Daniel Gibson for a 3-pointer as the Cavs opened a seven-point lead.

"They shot two big threes that were daggers," Allen said.

Garnett inexplicably sat out the first five minutes of the fourth, and made just 2 of 9 shots after going 4-for-4 in the first.

When Garnett dropped his first jumper, former Celtics player and current broadcaster Cedric "Cornbread" Maxwell removed his headphones, stood up and screamed, "Get down in the box," toward the floor below.

Garnett seemed to hear him as he scored nine of Boston's first 11 points. But with Varejao fronting him, Garnett got few other good looks at the basket in the first half and was even quieter after halftime.