Toulon centre Mathieu Bastareaud explained why he is headed for New York after the Rugby World Cup.
Greig Laidlaw's boot and a pair of tries from Apisai Naqalevu helped Clermont Auvergne battle back to beat Stade Francais on the road.
Top 14 leaders Toulouse enjoyed a fine day as several rivals were beaten amid a series of dramatic finishes.
Franck Azema will become the longest-serving coach in Clermont Auvergne's history if he sees out a new deal until 2023.
England international Ben Te'o is one of eight players who will be leaving Sixways at the end of the Premiership season.
Sunday's semi-final against Leinster will see Toulouse players wearing a special kit that includes an image of Notre Dame.
After a run of six defeats in their last seven Top 14 games, Simon Mannix has stepped down as Pau's sporting director.
Sofiane Guitoune's 77th-minute try carried Toulouse past Clermont Auvergne as the top two in the table served up a Sunday treat.
La Rochelle put Pau to the sword and Castres also enhanced their chances of reaching the play-offs with a win in Bordeaux.
Clermont Auvergne had to settle for a draw against Racing 92, while Lyon held on to beat Pau in a thrilling day of Top 14 action.