(CNN) -- The new-look Miami Heat insist it is too early to judge their NBA title credentials after losing their opening game of the season 88-80 to the Boston Celtics on Tuesday.
In one of the most highly-anticipated games in the series' history, the Heat -- complete with their star trio of Dwayne Wade and new signings Chris Bosh and LeBron James -- could not live up to close season expectations against the 17-time NBA finals champions.
But James -- who announced his decision to leave the Cleveland Cavaliers to join Miami in dramatic fashion on an hour-long television program on ESPN in July -- believes his new team can improve sufficiently before the end of the season in April next year.
"It's a feel-out process,'' James told the official NBA website after the loss. "Rome wasn't built in one day, it's going to take time. We understand that."
"This is one of 82 [games],'' added Wade. "Sorry if everyone thought we were going to go 82 and 0. It just ain't happening.''
Dubbed as the NBA's new "dream team," the Heat were greeted with chants of "overrated" from the packed crowd at the TD Garden arena in Boston, as they struggled to score just nine points in the first quarter and found themselves trailing 45-30 at half-time.
Returning from a hamstring injury, Wade finished with 13 points and Bosh made just eight. James, the final member of "The Big Three" led the team with a total of 31, but despite scoring 21 in the final quarter his effort was still not enough to topple the defending Eastern Conference champions.
Boston were by far the more consistent side with Ray Allen scoring 20 for the east coast team, while Paul Pierce added 19 and Kevin Garnett contributed 10.
Shaquille O'Neal -- James's former teammate in Ohio and part of Miami's NBA finals winning team along with Wade in 2006 -- scored nine points on his debut for the Celtics.
Rajon Rondo also made 17 assists for the east coast team -- only two more than the whole of the Heat put together.
Boston will next take on the Cleveland Cavaliers away on Wednesday, while Miami will be hoping to get their first win of the season against Philadelphia also on Wednesday.
Also in action in the Western Conference on Tuesday were defending champions the L.A. Lakers, who beat the Houston Rockets 112-110.
Kobe Bryant finished with 27 points and Spain's Pau Gasol with 29, as the Californian side opened the defense of their title.
But the Texan side made the champions work hard for their victory at the Los Angeles Staples Center, with the two teams trading the lead four times in the final minute of play.
Elsewhere, the Portland Trailblazers recorded their first win of the season after defeating the Phoenix Suns 106-92.
The Blazers trailed 81-75 going into the final quarter of the game, but outscored rivals the Suns 31-11 in the closing stages.