Rassie Erasmus will work with the Bulls in pre-season as South Africa look to help their Super Rugby franchises in a Rugby World Cup year.
Ireland have secured the services of fly-half Johnny Sexton until at least 2021 after he signed a new contract on Tuesday.
Rassie Erasmus has inspired a South Africa turnaround but insists he will not remain as head coach beyond the 2019 World Cup in Japan.
Michael Cheika led Australia to the World Cup final in 2015 and he will soon learn whether he will take them into the 2019 tournament.
England lock Marto Itoje will be fit in time for the Six Nations, despite his recent knee injury, according to Saracens boss Mark McCall.
Premiership leaders Saracens made it three wins from three in the European Champions Cup after victory over Cardiff Blues on Sunday.
There were wins for the Ospreys, Sale Sharks and Clermont Auvergne in the European Challenge Cup on Saturday.
There were wins for Gloucester, Toulon and Leinster in the European Champions Cup on Saturday.
There were wins for Ulster and Edinburgh over the Scarlets and Newcastle Falcons in the European Champions Cup on Friday.