LONDON —  LeBron James and Kobe Bryant took a seat, then the U.S. Olympic basketball team took control.

The Americans got their expected blowout and fans got the show they came to see in the 110-63 win over Tunisia, but only after U.S. coach Mike Krzyzewski started his reserves to open the second half after a lackluster first 20 minutes.

Finally pulling away behind the second unit’s impressive second-half start, the Americans had six players in double figures and improved to 2-0 in the tournament.

Carmelo Anthony, Deron Williams, Russell Westbrook, Kevin Love and Andre Iguodala opened the third quarter with a 21-3 run, turning a surprisingly close 13-point lead into a 67-36 bulge before any of the more celebrated starters finally got to play in the second half.

“That was a great lift, man. That’s the best thing about this team, there’s no drop off,” said Kevin Durant. “We’ve got All-Stars off the bench. Those guys did great job for us.”

Anthony and Love scored 16 points apiece for the Americans, who gave the fans the dunk show they expected once the game was in hand. Durant had 13 and rookie Anthony Davis dunked his way to 12.

But they had to work hard to make this one look easy.

The game against the Olympic newcomers wasn’t expected to be close for more than a few minutes. The daily preview in the press center said it “could prove to be one of the most lopsided matchups of London 2012.”

The Americans maybe expected this would simply be like a practice — they even decided to cancel Wednesday’s workout some 11 hours earlier.

Yet they found themselves in a five-point game late in the first half, launching 3-pointers when they couldn’t be stopped inside.

Krzyzewski walked quickly toward the locker room at halftime and decided things would be different in the second half.

The second unit simply appeared to compete much harder, with Williams even playing one defensive possession with one shoe after the other fell off. Love briefly had to come out after banging knees, but was able to return later.

Makram Ben Romdhane scored 22 for Tunisia, the African champion playing in just its second Olympic game. A wire-to-wire loser Sunday against Nigeria, they’ll be able to tell their kids their first Olympic lead came against the powerful Americans.

The Americans had played nothing but top-level opposition of late, beating Argentina and Spain in their final two exhibition games before opening with a 98-71 victory over France. They played like they expected a little breather so they could concern themselves mostly with adjusting to the Olympic basketball arena and the international officiating that had them so perplexed in the first half Sunday.

But nobody told the Tunisians they were supposed to go down easily.

They began fearlessly, with Ben Romdhane driving all the way for a dunk — the type of athletic plays that are usually made by the Americans, not against them — to take an 8-4 lead. Tunisia still led by three with 2:39 left in the period before the U.S. second unit ran off the final nine points for a 21-15 advantage.

Tunisia tried to outwork their more talented opponents, hustling for loose balls to set up second shots that usually missed.

The Americans missed all eight 3-pointers in the first, even worse than their 0-for-6 start Sunday, before Anthony nailed one to open the second quarter. Westbrook followed with a jumper for a 26-15 lead, and the expected U.S. blowout seemed to be under way.

Instead, Marouan Kechrid made consecutive 3-pointers a couple of minutes later that brought Tunisia within six points, and he made another one with about 3  1/2 minutes left, pumping his fist back toward his bench after cutting the U.S. lead to 35-30.

Only then did the Americans finally get control of the game, rattling off 11 straight points, with James’ behind-the-back pass to Durant for a dunk making it 46-30. The Americans led 46-33 at the half.

“We knew that they were going to come out and play hard,” Durant said. “We missed some shots early on and we gave up some easy baskets, but we came back and started fighting a little harder.”

The teams met in the 2010 world championship in a similar game. The U.S. won 92-57, pulling away after leading by just six at halftime and holding the Tunisians to 27.8 percent shooting for the game.

The Americans were 17 of 22 (77 percent) on 2-pointers in the first half, but missed 10 of their 12 3-point shots. They didn’t need to worry about 3s much in the second half — though those could become a problem against better competition — because they got dunks whenever they wanted.

Westbrook scored 11 for the U.S., which plays Nigeria on Thursday.