James O'Connor scored a brace of tries as Toulon climbed to within two points of the Top 14 summit with a 21-17 win over Pau.
The Australian winger's first score came in the 25th minute to give the hosts an 8-3 lead at the Stade Fleix-Mayol, after Tom Taylor and Colin Slade had exchanged penalties.
Further scores from Kote Mikautadze and O'Connor then helped Toulon build a 21-3 advantage with 26 minutes left, before the visitors set up a nervy finish.
Rugby World Cup winner Conrad Smith notched a converted try before a late penalty try cut the deficit to just four points, but Toulon were able to hold on.
Stade Francais stunned Toulouse in the late game, Paul Williams scoring a 78th-minute try to snatch an 18-17 win for the defending champions. Toulouse's losing bonus point left them locked in a three-way tie with Racing 92 and Clermont Auvergne on 38 points at the top of the table.
Alexis Palisson scored a try for Toulouse in the fourth minute, and Sebastien Bezy kicked four penalties for the visitors, but Hugo Bonneval and New Zealand-born centre Williams touched down for Stade and Jules Plisson landed two penalties and a conversion for the hosts.
"I would be lying if I said I wasn't relieved and extremely satisfied to win that match," Stade manager Gonzalo Quesada said.