Greig Laidlaw kept his cool to maintain Clermont Auvergne's perfect start to the new Top 14 season.
Clermont won an early top-of-the-table clash with Stade Francais, while there were also Top 14 victories for Racing 92, Toulouse and Lyon.
Clermont Auvergne made the most of a chaotic spell in which Racing 92 were reduced to 13 men, triumphing in Top 14 on Sunday.
Racing 92 have been given a boost ahead of the new season, with Henry Chavancy, Eddy Ben Arous and Camille Chat signing contract extensions.
Racing 92 pushed late on, but they were unable to find a way past Castres in the Top 14 semi-finals.
Following his side's Champions Cup defeat to Leinster, Leone Nakarawa of Racing 92 was named European Player of the Year by EPCR.
Leinster were playing catch-up in Saturday's European Champions Cup final against Racing 92 until the last couple of minutes.
Just as they did in 2009, 2011 and 2012, Leinster tasted European Champions Cup glory as Racing 92's stern resistance proved in vain.
A hamstring injury has cruelly denied Dan Carter a role in Racing 92's European Champions Cup final against Leinster.
Racing 92 stand between Leinster and a record-equalling fourth European Champions Cup win, which is Johnny Sexton's sole focus.