Wales international George North will swap Northampton Saints for Pro14 side the Ospreys, the WRU has announced.
Ulster maintained its late push to qualify for the Pro14 play-offs with a thrilling 36-15 victory against Glasgow Warriors.
Benetton Treviso stunned Leinster with a 17-15 Pro14 win over the Conference B leader and Edinburgh dished out an eight-try hammering to the Scarlets on Sunday (AEST).
Glasgow Warriors was handed just its third Pro14 defeat of the season against Scarlets on Sunday (AEST), while Benetton Rugby and Cheetahs both edged tight thrillers.
Cardiff Blues made it five wins in a row in the Pro14 with a 35-17 victory over Ulster, keeping its late surge for the play-offs alive.
Niel Marais kicked a last-minute penalty to earn Cheetahs a 26-25 victory over Connacht for a first Pro14 triumph since January.