Bordeaux, who amassed more points than any other team in the group stage, soaked up late pressure and were good value for a last 16 first-leg win that makes them favourites to progress ahead of the return at the Stade Chaban-Delmas on March 17.
"We played very well. We came to show we are serious competitors in this competition and we displayed this during the course of the match," Blanc told reporters after Ciani's winner in added time at the end of the first period.
"We scored a goal at an important point in the first half. In the second half we left too much space for Olympiakos and there were spells when I felt we could have been more aggressive but in general I am satisfied," added Blanc.
"I believe my players and the team knew what they were doing out there and they showed me what I was expecting to see.
"I believe that generally we played a good game. We showed organisation and stability. We came here in order to see what our chances were of progressing and with this result we have increased our chances of reaching the quarter-finals."
STRONG START
Olympiakos had booked their place in the last 16 by finishing second in Group H thanks largely to their home form and, roared on by a typically passionate crowd, began strongly.
Olof Mellberg threatened first, heading Jesus Datolo's free-kick just wide after four minutes. Wingers Datolo and Lomana Lua Lua also saw plenty of the ball early on and had Bordeaux on the back foot with their pace and trickery.
The home side's best chance of the game came with just under 10 minutes lift when former English Premier League forwards Matt Derbyshire, on as a second half substitute, and Lua Lua combined bur the latter saw his shot tipped around the post.
The hosts, who were playing in their 200th European game, had a goal chalked off in the closing seconds as they pushed for an equaliser, Derbyshire adjudged to having fouled goalkeeper Cedric Carrasso as Enzo Maresca nodded home from close range.
"I consider that we were very good today," said Olympiakos coach Bozidar Bantovic. "This was one of our best games this year. The players gave their all for the entire 90 minutes."
"We know that our opponents are strong at home but if we play like we did today we have nothing to fear. We will go there looking for the win which will give us qualification."
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