Nonu and Mitchell stars for Toulon
Nonu scored the first of his team's six tries in the 13th minute after Wallaby wing Mitchell had broken the line before off-loading to the centre.
Twenty minutes later, Nonu was heading for the sin-bin after a crude shoulder charge on opposing flyhalf Christophe Loustalot. It was the 33-year-old centre's first yellow card in the Top 14.
Mitchell scored his tries in the 50th and 70th minutes, the first after an imposing ruck and the next after being set-up by Eric Escande.
"He is getting used to his teammates better. In rugby this can take a little time but he always has interesting matches," said Toulon boss Bernard Laporte said of Nonu.
Top 14 results:
Stade Francais 16-34 Racing
Clermont 25-6 Brive
La Rochelle 35-16 Pau
Castres 50-6 Agen
Toulon 38-8 Grenoble
Toulouse 13-13 Bordeaux-Begles
Top 14 table:
(played, won, drawn, lost, points for, points against, bonus points, penalties, total points)
Racing 92 17 13 1 3 390 302 5 59
Clermont 17 11 1 5 482 285 12 58
Toulon 18 11 0 7 556 327 13 57
Bordeaux 18 11 2 5 390 320 4 52
Toulouse 17 9 2 6 434 269 8 48
Montpellier 16 10 0 6 401 385 5 45
Castres 17 9 0 8 393 338 7 43
La Rochelle 17 8 0 9 373 370 8 40
Brive 17 8 1 8 311 333 4 38
Grenoble 17 7 0 10 411 483 5 33
Pau 17 6 1 10 264 448 2 28
Stade Francais 17 6 0 11 323 388 2 26
Agen 17 3 0 14 328 530 3 15
Oyonnax 16 3 0 13 269 547 2 14
Agence France-Presse
