World champions Japan will face the USA in the final of the women's football competition after surviving a bold France fightback.
Yuki Ogimi scored from close range after a mistake from keeper Sarah Bouhaddi, and Mizuho Sakaguchi extended the lead with a brilliant header.
Eugenie Le Sommer pulled a goal back for France with a strike from 10 yards.
Elise Bussaglia should have equalised but her penalty drifted agonisingly wide of the post as Japan held on.
"On chances created, France were definitely the more attacking side with a lot more shots on goal, but Japan are renowned as being a disciplined team and they've taken their chances."
Japan, who beat the US on penalties in last year's World Cup final, will contest their first Olympic final at Wembley on Thursday.
But it was a close-run thing, as France dominated after falling two goals behind, with substitute Le Sommer and Louisa Necib particularly influential.
There had been precious few chances before Japan took the lead just after the half-hour mark.
France keeper Bouhaddi flapped at a free-kick directed into a packed penalty box and Ogimi reacted more quickly than several French defenders to slot home from close range.
And Japan tightened their grip on the contest shortly after the restart when the France defence failed to deal with another free-kick.
Sakaguchi found space in a packed penalty box to execute a brilliant header, which she directed beyond Bouhaddi and into the far corner.
Women's semi-final line-up
- Canada v United States (Old Trafford)
- France 1-2 Japan (Wembley)
The Japanese, who finished fourth in Beijing, were precise in their passing and organised in defence - and for a long time France struggled to break them down.
Bruno Bini's side tried to force their way back into the contest but Necib shot wastefully over with a good opportunity after a surging run from Marie-Laure Delie, who also missed from 18 yards.
Fukumoto made a brilliant one-handed save to thwart Necib as France finally found some penetration, but the Japan keeper could not get near Le Sommer's shot after she met Delie's cut-back with a first-time strike.
France should have levelled after Sakaguchi brought down Le Sommer but Bussaglia missed the target after sending the keeper the wrong way.
Ogimi should then have scored on the break to seal Japan's win but missed from eight yards with only the keeper to beat, while Fukumoto denied France's Wendie Renard in injury-time.