Paris - All Black great Ma'a Nonu gave away a late penalty converted by Baptiste Serin which cost Toulon the chance to move top of the French league on Sunday.
Nonu's gaff allowed scrumhalf Serin to kick a penalty a minute from time that gave Bordeaux-Begles a 15-12 victory.
European champions Toulon would have gone top of the league with a victory but instead remain third, while Bordeaux move up two places to fifth in the Top 14 table.
In a match brought forward from the weekend programme of March 19, Toulon scrumhalf Jonathan Pelissie was embroiled in a kicking contest with Bordeaux flyhalf Simon Hickey.
Pelissie struck first in the 16th minute but after New Zealander Hickey replied five minutes later, the former Blues player gave the hosts the lead three times, only for the Toulon scrumhalf to reply shortly afterwards every time.
The match seemed to be petering out into a draw, although Toulon were pushing for a winning score when they kicked a penalty to the corner late on.
But Bordeaux forced a turnover and replacement flyhalf Yann Lesgourgues made a 60-yard break before being hauled down by Eric Escande on the Toulon 22.
The over-eager Nonu, who retired from international rugby following New Zealand's successful World Cup defence in October, went offside at the resulting ruck and Serin was left with a relatively simple penalty to claim the victory.
This match was originally schedule for January but was postponed along with the entire programme to accommodate previously called off European games.
In the wake of the Paris terror attacks last November, all sport in the country was suspended for a little over a week, meaning several European Champions Cup and European Challenge Cup matches had to be rearranged.
They were moved to the weekend of January 8-10 meaning the scheduled Top 14 games had to be switched.
With a break in the Six Nations next weekend, a full programme of matches will take place in France with Toulon away to Oyonnax and Bordeaux playing Agen.
Racing 92 remain top above Toulouse, both just a point ahead of Toulon.