Japan, bidding to add Olympic gold to the World Cup title they won last year, were held to a goalless draw by Sweden in their second group match on Saturday.
Both sides came into the Group F clash on the back of wins, with Japan having defeated Canada 2-1 in their opener and Sweden thrashing South Africa 4-1.
But clearcut chances were in short supply at the City of Coventry Stadium in the English Midlands, although it needed some sound saves from Sweden goalkeeper Hedvig Lindahl to keep this match scoreless.
Japan saw Aya Sameshima try her luck midway through the first half before Sweden striker Sofia Jakobsson's effort just drifted wide of the post.
Lindahl did well to deny Nahomi Kawasumi early in the second half and the Sweden keeper was quickly off her line to snuff out a promising break by Yuki Ogimi.
And in the 69th minute Lindahl ensured the game remained goalless with a smart save from Shinobu Ohno.
The United States, the reigning Olympic champions, are in action later Saturday against Colombia having had to come from two goals down to beat France 4-2 in their opener.
Meanwhile Formiga, the only women's footballer to have competed in all five Olympics since the sport was introduced to the Games, will play her 100th match for Brazil if she is selected against New Zealand at Cardiff's Millennium Stadium.