GB, USA and Brazil go through
Captain Casey Stoney set them on their way with a close-range finish in the 18th-minute, with Jill Scott adding the second five minutes later. Steph Houghton, the heroine of the opening win over New Zealand, sealed the win with her fierce strike eight minutes from time.
And with Brazil and GB having recorded two wins from two in Group E, both sides are guaranteed a last-eight berth ahead of their meeting at Wembley on Tuesday.
There were moments of concern for coach Hope Powell thanks to some robust tackling from the African opponents, although it was an innocuous challenge from Ajara Nchout that saw defender Ifeoma Dieke leave the field on a stretcher during the second half.
Brazil striker Cristiane pounced on a poor clearance late on to break New Zealand hearts with a 1-0 win in the early match at the Millennium Stadium.
New Zealand had frustrated Brazil thanks to a disciplined defensive display and looked set to hold the Samba Queens to a goalless draw. But stiker Cristiane, who plays her club football in Russia with WFC Rossiyank, calmly lobbed Ferns' goalkeeper Jenny Bindon after her punch went straight to the Brazilian.
"New Zealand are a very good team, very organised," said match-winner Cristiane. "Nobody said any of these matches at the Olympics were going to be easy."
The victory meant Brazil, silver medallists at the last two Olympics, made it two wins out of two at London 2012 after thrashing Cameroon 5-0 in their opening game.
Reigning Olympic champions the United States secured their progress into the quarter-finals with a regulation 3-0 win over Group G opponents Colombia.
Megan Rapinoe opened the scoring with a fine dipping shot from outside the area on 32 minutes and the US would have been further ahead at the break but for two desperate goal line clearances from Colombian captain Natalia Gaitan.
Abby Wambach did eventually make the Americans' domination count 17 minutes from time and Carli Lloyd rounded off an excellent team move for the third three minutes later.
Group G rivals France revived their London 2012 hopes with a thumping 5-0 win over Korea DPR, which was inspired by their speedy supersub Elodie Thomis.
Women's World Cup holders Japan failed to capitalise on their territorial dominance and were held to a goalless draw by Sweden in their Group F clash at the City of Coventry Stadium.
Japan had enough chances to have won comfortably but were let down by poor finishing and some fine saves from Swedish goalkeeper Hedvig Lindahl.
After the match, Japan captain Aya Miyama said: "We are not very happy. We want to get a gold medal and win all our matches so we are quite disappointed."
Also in Group F Canada proved too strong for South Africa, winning 3-0 thanks to two goals from captain Christine Sinclair and one from fellow forward Melissa Tancredi.
Canadian skipper and record scorer Sinclair took her tally for her country to 139 after Tancredi had opened the scoring by netting for the second successive match. She is now only 19 short of the highest-ever tally in women's football of 158 by Mia Hamm of the United States.
Coach John Herdman said: "That is the player Christine is. You can contain her for a period of time but when she is on song, she is on song. That is truly the mark of a great player in that some days they are unstoppable."
