Scott, the 2011 world champion, held onto his lead in the Finn class after the last two outings before Saturday's medal races, claiming a win and third on the French waters.
Mills meanwhile was second in both races with the deficit between himself in second and Scott, who won the last World Cup in Palma, in the lead increasing from five points to six.
ISAF's scoring experimentation is continuing in Hyeres which means there are two double-points medal races for the top ten boats in each Olympic class aside from the 49er and 49erFX.
Ed Wright and Mark Andrews will join the two Brits in the medal race after placing eighth and tenth overall respectively and Mills is ready to give Scott a run for his money.
"Both of them could have been firsts at points so that was a little bit annoying but I can't really complain. Two seconds is alright," said Mills.
"It was a shifty kind of day, so it was about playing it consistently, not hitting the corners and having relatively good boat speed around the track.
"I think [Giles] has got one point further ahead, so six points behind going into a 40-point day is a reasonable place to be I'd say.
"It should be good. I quite like the medal races. Of the new format, two medal races is something I don't think is a bad thing. The qualifying series I don't like but the medal races should be good."
A number of other Brits are also in medal contention going into the medal races with Alison Young cutting the gap on leader Marit Bouwmeester to just one point in the Laser Radial.
Bryony Shaw is also placed second in the women's RS:X but 11 points behind Charline Picon while Ben Saxton and Hannah Diamond are fifth in the Nacra 17 currently a point off third.
They will be joined in the medal race by Lucy Macgregor and Tom Phipps while Luke Patience and Joe Glanfield and Sophie Weguelin and Eilidh McIntyre will do battle in the men's and women's 470.
Nick Thompson did just enough to make the Laser medal race in tenth overall while two British crews go in the 49erFX showdown and three in the 49er.
Three double-points medal races are scheduled for the top-eight boats in both classes with Charlotte Dobson and Mary Rook second in the 49erFX and Penny Clark and Sophie Ainsworth eighth.
Britain currently sweep the top three in the 49er with Dave Evans and Ed Powys leading but tied on points with Dylan Fletcher and Alain Sign whole Stevie Morrison and Ben Rhodes are third.
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