The United States women's basketball team extended their Olympic winning streak to 34 games with a 81-56 win over Croatia.
The Americans, chasing a fifth straight gold and defending an unbeaten run that dates back to 1992, conceded an early lead to leave themselves locked in a close battle for most of the second and third quarters.
But as the game moved into the final stanza they began to make some defensive stops and break away for easy baskets, finishing the game on a 30-9 run.
Tina Charles led the Americans with 14 points while Angel McCoughtry added 13 and Candace Parker 11 with 13 rebounds.
Jelena Ivezic had 22 points for Croatia, with Marija Vrsaljko registering 19.
"I think you're going to see that a lot," said United States point guard Sue Bird of the late surge. "Our biggest advantage over most teams is our depth and our ability to just keep throwing people at you and wear you down."
Great Britain's women could not mark their Olympic debut with a victory but they certainly put in a battling performance as they lost 74-58 to world number two Australia.
On an emotional night for the players, there were some rushed shots and bad decisions but never any shortage of fight as they made mistakes but forced plenty too.
However, poor shooting stopped them from pushing Australia any closer, as they made only seven of 30 from the field in the first half, and finished 20 of 68 for the game.
Jo Leedham and Rachel Vanderwal finished with 11 points each for Britain, while Natalie Stafford had 10.
Lauren Jackson led Australia with 18 in the Group B fixture.
In Saturday's other Group A games, China knocked off the Czech Republic 66-57 to get the tournament going with an upset, while Turkey brushed aside Angola.
A hot start gave the Chinese a 15-4 lead over the 2010 world championship runners-up, and although the Czechs closed the gap to 20-16 by end of the first quarter, China kept them at arm's length.
It was not until the third quarter that they drew level, 55-55, on Michaela Zrustova's three-pointer, but they looked to have little left in the tank as China finished on an 11-2 run to take the win in Group A.
"The weak beat the strong," said China coach Sun Fengwu.
His opposite number Lubor Blazek cut a more dejected figure.
"In the beginning, we let the Chinese overplay us," he said. "All game long we were trying to catch up. What we needed was just one time to lead by a couple of points for my team to calm down."
Ma Zengyu led China with 16 points while Miao Lijie added 12 and dished out eight assists.
Eva Viteckova had 14 points for the Czech Republic.
Early on Saturday morning, the second Group A game of the day saw Turkey cruise to a 72-50 win over Angola.
Turkey scored the first 13 points and were up 20-2 late in the first quarter.
Angola, making their first Olympic appearance, got it back to 35-25 at half-time, but Turkey began the second half on another tear to put it out of reach.
Emine Palazoglu led Turkey with 13 points.
In Russia's Group B opener, Becky Hammon scored eight of her 14 points in the final 2:40 of the game as they stormed back from a 10-point deficit in the fourth quarter.
Canada had led almost the entire game after cancelling out Russia's 10-3 start, and they were 50-40 up with 6:33 to go.
But after back-to-back threes from Anna Petrakova and Alena Danilochkina, Hammon tied it 50-50 and then took over in the closing stages.
The veteran guard had struggled early, making only two of 15 shots in the first half, but found her form when it mattered.
"I couldn't throw it in the ocean if I was sat in a boat (in the first half)," she said. "But you keep working and my team-mates told me to keep shooting. You just keep playing and hope good things will happen."
Kim Smith scored 20 points for Canada, sinking five-of-seven three-point attempts.