Cleveland’s LeBron James (23) shoots over Atlanta’s Al Horford (15). The Cavaliers ripped Atlanta, 99-72, on Tuesday in Cleveland.

Cleveland ? Alone under his basket, LeBron James braced himself for Atlanta’s onslaught.

As two Hawks swooped down on a fast break, James held his ground, stepped in front of Joe Johnson and took the charge.

The only play. The smart play. A game-changing play for Cleveland.

MVP. Indeed.

James dunked the first time he touched the ball and scored 34 points — 22 in the first half — as the Cavaliers, who waited nine days between playoff games after a first-round sweep, shook off some early rust and pulled away for a 99-72 victory over the Hawks in their Eastern Conference semifinal opener on Tuesday.

Showing why he was voted the league’s best player in a landslide, James added 10 rebounds, three assists and four steals as the top-seeded Cavs won their fifth straight lopsided game in a postseason that has so far mirrored the best regular season in franchise history.

James stuffed the stat sheet again, but it was his defensive stop on Johnson in the third quarter that meant as much as anything.

“An MVP taking a charge on the break?” Cavs guard Mo Williams said. “That’s amazing. You get that effort from him, how could I not take a charge? The whole night was about him and he came out and showed why he is the MVP — in the first quarter.”

The Cavs weren’t sure how the layoff would affect them.

“It was unbelievable how sharp we were,” James said. “We just picked up where we left off.”

Williams added 21 points for Cleveland, which became the first team since the 2004 Detroit Pistons to win each of its five playoff games by double figures.

With the Cavs up by 21, James was pulled with 4:29 left — extra down time before Game 2 on Thursday night at Quicken Loans Arena, where the Cavaliers are 42-2.