Toulon return to top, Williams yellow-carded on debut
Toulon's centre Rudi Wulf (C) is tackled by Bayonne's defenders during a French Top 14 rugby union match on September 21, 2013, at the Mayol stadium in Toulon, southeastern France.
The European champions were behind three times to a team they had crushed 50-10 and 59-0 on their last two visits.
But they were saved by tries in either half from wingers Josua Tuisova and David Smith.
Jonny Wilkinson added eight points with the boot while former Crusaders and Blues fly-half Stephen Brett slotted over four penalties for Bayonne.
European champions Toulon, defeated 22-15 by Castres last week, were plagued by indiscipline with lock-forward Williams and South African scrum-half Michael Claassens both handed second-half yellow cards.
The 32-year-old, 77-capped Williams, who only arrived in France three days ago, was sin-binned for stamping in the 61st minute.
"What worries me is that we are first, it's worrying for French rugby!" said Toulon coach Bernard Laporte.
"We did everything we should not have done in a rugby match in 80 minutes."
Stade Francais moved into second spot, also on 22 points, after ending promoted Oyonnax's 22-month undefeated home run with a 16-15 win.
But victory was only secured in the 74th minute when Hugo Bonneval grabbed the lone try of the game, converted by Julien Dupuy.
Montpellier are in third place, one point off the lead, while Toulouse, also on 21 points, continued their winning home form with a welcome bonus-point 26-9 victory over defending champions Castres.
Former All Black playmaker Luke McAlister scored a try and kicked 11 further points, proving instrumental in Toulouse's high-octane off-loading game that shone through after a mistake-ridden opening 40 minutes.
"This is an unexpected result," admitted Toulouse backs coach Jean-Baptiste Elissalde.
"We hadn't counted on a bonus-point victory. We just wanted to continue to put a little more of everything in our rugby compared to the first six matches."
McAlister got the scoreboard ticking with an eighth minute penalty.
Another Kiwi, centre Daniel Kirkpatrick, deputising for benched South African scrum-half Rory Kockott, pulled Castres level with a penalty of his own soon after.
Former Hurricane Kirkpatrick was successful with his second but Toulouse hit back immediately.
A break by fast-footed France centre Gael Fickou broke down but the ball was recycled and worked back across the park, scrum-half Jean-Marc Doussain crossing in the corner for a try McAlister was unable to convert.
McAlister was on target for his second penalty on the stroke of half-time.
Kirkpatrick saw an early second-half penalty come back off the woodwork as Toulouse tried to up the ante with their off-loading game.
While guilty of trying to force too many passes, Toulouse's pressure did pay off with another McAlister penalty.
Talismanic Kockott came on for Castres in the 57th minute but it was not enough to prevent McAlister crashing through a weak Kirkpatrick tackle and over for a converted try after a strong attacking scrum.
Kockott, who qualifies for France in June on residency rules, pulled one penalty back for the visitors.
But Toulouse had the last word, a Florian Fritz turnover freeing up Yacouba Camara in midfield, the teenage replacement flanker riding two weak tackles for a fine try.
Racing Metro are fourth, a point behind Montpellier and Toulouse, thanks to a 26-19 home win over Bordeaux-Begles.
Marc Andreu grabbed a brace of tries within four first-half minutes while Irish international fly-half Jonathan Sexton added a third try after the break. It was Racing's third successive victory.
In Friday's game, scrum-half Jonathan Pelissie scored 31 points as Montpellier routed Clermont 43-3 in a bonus-point victory.