Lakers Putting Doubts to Rest : Basketball: Their 12-game winning streak serves notice that the club, after a shaky start, is still an NBA powerhouse.

The Lakers lost five of their first seven games and put their NBA powerhouse status in jeopardy. Now they’re erasing those doubts.

The Lakers extended their winning streak to 12 games Tuesday night, beating New Jersey 110-89 at the Forum, where they have a 16-1 record after losing three of their first four games. (Story, C1.)

“The Lakers are a totally different team out here,” the Nets’ Reggie Theus said.

The string of wins is the longest of the season in the NBA. Portland opened the season by winning its first 11 games.

“We’ve improved tremendously from the beginning of the season,” Magic Johnson said. “If you look from where we started to where we are now, we are headed in the right direction.

“And the only thing I see ahead of us is better things. So I’m happy with our progress.”

Progress is putting it mildly. Since their sluggish start, the Lakers have been on a roll, winning 29 of 35 games. Before beating the Nets Tuesday night, they completed a perfect five-game, seven-day road trip on Sunday with a convincing 104-87 over the Boston Celtics at the Boston Garden.

At 31-11, the Lakers have the same record they had at this time last season when they won a league-best 63 games.

Actually, the Lakers’ poor start was a little misleading. Their early schedule was difficult, and they were playing under a new coach, Mike Dunleavy, who replaced Pat Riley after he left to become a television commentator.

After losing at San Antonio in their season opener, the Lakers were beaten in overtime by Portland at the Forum. Then came a victory over Sacramento and close home-court losses to the New York Knicks and the Phoenix Suns, the team that eliminated the Lakers from the playoffs last season.

Finally, the Lakers won at Houston and lost at Dallas before heating up.

What turned L.A. around? Several things.

It took a while for the Lakers to adjust to Dunleavy’s system and it took some time for free-agent acquisition Sam Perkins to get rolling.

Neither starting center Vlade Divac nor shooting guard Byron Scott was very effective early. They have been lately.

Johnson is having another great season, as is forward James Worthy, and several reserves have done their parts.

Dunleavy made it clear after the tough start that he wasn’t about to panic. And although he expressed frustration, Johnson said the same thing.

Now, all is well.

Shortly before starting their current winning streak, the Lakers served notice that they were back to their form of the 1980s when they beat the Trail Blazers 108-104 at Portland on Jan. 3.

The Lakers are making Dallas center James Donaldson look like a poor prophet. After the Mavericks beat Los Angeles 99-86 on Nov. 16 in the seventh game of the season, Donaldson said: “Anybody can look up and see this isn’t the Laker team that dominated us for the last few years. It’s still the Lakers on the uniform but not the Lakers on the court.”

The way the Lakers are playing now, Donaldson may change his mind.