Luka Doncic and the Dallas Mavericks have gone from long shots to Western Conference champs, but they're underdogs against the Boston Celtics in a star-studded NBA Finals matchup.

The Celtics opened as -225 favorites Thursday at ESPN BET. The Mavericks were listed as +185 underdogs after their clinching Game 5 blowout of the Minnesota Timberwolves in the Western Conference finals. The Celtics opened as 6-point favorites over the Mavericks in Game 1, which will be played June 6 in Boston.

Boston's Jayson Tatum was the betting favorite for Finals MVP at -130 Thursday at FanDuel, with Doncic next at +200. The Celtics' Jaylen Brown was +600, followed by Dallas' Kyrie Irving at +2,400.

The Mavericks began the season as around 25-1 long shots to win the title and saw their odds drift to 50-1 at some sportsbooks in January. But Dallas upgraded its roster at the trade deadline and impressed oddsmakers during the playoffs.

"At the start of the playoffs, this potential series price would have had the Celtics a heavier favorite, but now looks quite a bit closer," sports trader David Lieberman, who oversees NBA odds for Caesars Sportsbook, told ESPN.

Boston raced through the Eastern Conference playoffs despite losing center Kristaps Porzingis to a calf injury in the opening round. The Celtics were favored by at least seven points in each of their 14 playoff games this season.

Jeff Sherman, vice president of risk for the SuperBook in Las Vegas, said the opening price on the Finals reflects Porzingis returning to the lineup.

"I'm expecting Dallas support [from bettors]," Sherman said.