European Professional Club Rugby has confirmed the new dates and kick-off times for the five matches in the European Rugby Champions Cup originally postponed due to the terror attacks in Paris last month.
Munster will travel to Paris to face Stade Francais in Pool 4 at Stade Jean Bouin at 4.45pm Irish time on Saturday, 9 January.
Ulster will face Oyonnax a day later at Stade Charles Mathon in Pool 1 at 1pm Irish time.
Elsewhere, Top 14 rivals Bordeaux-Begles and ASM Clermont Auvergne meet at Stade Chaban-Delmas in Pool 2 on Friday, Racing 92 and Glasgow Warriors meet at Stade Yves-du-Manoir in Pool 3 on Saturday, and Toulon and Bath clash at Stade Felix Mayol on Sunday.
The reconfigured programme of matches means that the 12th round of games in the Pro12 will be rescheduled for later in the season, while the Top 14 and Aviva Premiership will also need to alter their fixture lists.