INDIANAPOLIS — Thaddeus Young, with the ball and an open court ahead of him, was focused on fending off the Cleveland Cavaliers’ J. R. Smith and extending to the rim for a layup. It seemed simple enough. But Young, the starting power forward for the Indiana Pacers, forgot. He forgot about the best player in the world.

LeBron James, who was trailing the play, began to eat up ground as he crossed midcourt, and an expectant hush fell over Bankers Life Fieldhouse. It was just a matter of watching the inevitable play out: James soaring to block Young’s shot from behind, the ball landing among James’s teammates on the bench, and James’s momentum carrying him into the tunnel behind the basket.

“I was actually going to go for my little ‘Forrest Gump’ thing and just keep it moving,” James said. “But there was more basketball that needed to be played.”

The play was reminiscent of James’s chase-down block on the Golden State Warriors’ Andre Iguodala in Game 7 of last season’s N.B.A. finals, and another indication — as if anyone needed one — that Playoff LeBron is back. The Cavaliers may have had ups and downs during the regular season, but they began the playoffs with a four-game first-round sweep of the Pacers that they completed with a 106-102 victory on Sunday.