Stade storm back to top in France
Stade Francais's captain Sergio Parisse (C) celebrates with his teammates Anton van Zyl and Morne Steyn during a French Top 14 rugby union match against Castres Olympique on January 24, 2014 at the Jean Bouin stadium in Paris - by Pierre Andrieu
Stade ran in three tries -- all in the second half -- after South African stars Morne Steyn and Rory Kockott had kicked all the points in the first half with Stade ahead at 12-6.
Fijian winger Waisea Vuidravuwalu scored two of Stade's tries in the space of seven second-half minutes as his team went two points clear of Clermont at the top of the table.
Clermont can retake pole position with a win at Bayonne on Saturday.
"The squad was really together this week with the ambition of staying in the top six and not get into difficulty ahead of two matches in the Six Nations," said Stade boss Gonzalo Quesada.
"We have sincere pride and good sensations after this win."
Steyn, getting a start in the Stade line-up after Jules Plisson became one of Stade's six players on Six Nations training duty this week, succeeded with his first two penalties for a 6-0 lead.
His fellow South African, Kockott cut the lead with a penalty of his own.
As the errors piled up, Steyn missed the target while Kockott saw his second pot at goal come back off the upright.
Steyn succeeded with a 30-metre effort and exchanged successful kicks with Kockott as Stade led 12-6 at the interval with Castres paying a heavy price for conceding a total of eight penalties.
Steyn missed a 40-metre penalty early in the second half before Stade's American lock Scott LaValla had a try ruled out for a double movement as he struggled over the Castres line.
However, the Paris giants did deservedly grab the opening try moments later when French winger Julien Arias finished off a move involving Hugo Bonneval and South African centre Meyer Bosman.
That gave Stade a 17-6 lead and although Steyn missed the conversion, he was successful with another penalty when Castres' Kiwi import Karena Wihongi was yellow-carded.
Castres wilted and Vuidravuwalu seized his opportunity to grab two quick tries to see Stade back to the top.