The Englishman landed five penalties and three conversions as his side leapfrogged Clermont, though the match was not quite as one-sided as the scoreline suggested.
Steffon Armitage's try after 22 minutes put the visitors ahead, but the lead was just 13-9 at half-time thanks to two penalties by Matt Berquist and a drop goal by Damien Traille for Biarritz.
Toulon pulled clear in the second half with two penalties, but it was only late tries from Vincent Martin in the 76th minute and Matt Giteau in the 79th minute that put the result beyond doubt.
Three of the day's matches were thrillers decided in the final moments. A late penalty from Jerome Porical gave Stade Francais a 30-28 win away at Mont-de-Marsan, while Grenoble also won a thriller at the death at home against Perpignan as Aloisio Butonibualevu scored a try in the penultimate minute.
But the most incredible result came as Luke McAlister landed a penalty for Toulouse an astonishing seven minutes after the clock went in to the red to give his side a 34-32 win away at Bordeaux, who had been reduced to 13 men and had already been stunned by Toulouse's two tries in the final quarter of an hour.
Montpellier won 16-12 at Racing Metro and Bayonne hammered Agen 37-16.