Teddy Thomas scored a hat-trick as Racing 92 beat struggling derby rivals Stade Francais 25-9, while Top 14 leaders Lyon thumped La Rochelle on Sunday.
Stade remain rooted to the bottom of the table after Thomas bagged a treble at Stade Jean-Bouin to move Racing up three places to 10th and pile more pressure on coach Heyneke Meyer.
Meyer was backed by Stade owner Hans-Peter Wild on the eve of the Paris derby, but a seventh defeat from nine top-flight matches will lead to more questions over his future.
Wing Thomas took a brilliant pass from Virimi Vakatawa before scoring the opening try and had a double late in the first half, though a second Nicolas Sanchez penalty reduced Racing's lead to 15-6 at the break.
Maxime Machenaud's second penalty gave Racing a nine-point advantage and France flyer Thomas crossed for a third time right at the end to secure the bonus point, much to the fury of Racing fans.
Lyon are five points clear at the summit after a 45-17 battering of La Rochelle.
Baptiste Couilloud dotted down in both halves, while Dylan Cretin, Charlie Ngatai and Loann Goujon also crossed in an emphatic victory for the leaders.