The fixture list includes an exciting all-Guinness PRO14 clash too as Glasgow Warriors face Cardiff Blues at Scotstoun.
Elsewhere, reigning champions Leinster host Pool One front-runners and Top 14 giants Toulouse.
Munster have made a great start to their European campaign and will arrive for their clash against Gloucester as pool leaders, as will Edinburgh when they pay a visit to Toulon.
Here’s what you can expect from the six scheduled fixtures this weekend:
Gloucester Rugby v Munster Rugby (Friday, January 11 19:45, Kingsholm Stadium)
This round five opener will see high-flying Munster come up against a Gloucester side looking to recover from back-to-back defats.
Munster will arrive at Kingsholm sitting at the top of Conference A in the Guinness PRO14, as well as leading the pack in Europe.
Gloucester, on the other hand, have found life in Europe a struggle so far this season, with two wins and two losses not enough to keep them off the bottom of the pool.
Munster have won each of their last five encounters with the cherry and whites, all of those victories coming by a margin of at least 12 points.
“A massive game for both sides.”
— Munster Rugby (@Munsterrugby) 9 January 2019
Leinster Rugby v Toulouse (Saturday, January 12 13:00, RDS Arena)
Reigning European Rugby Champions Cup winners – and the team of the moment in the Guinness PRO14 – Leinster have been forced to play second-fiddle to Toulouse in Europe so far this season.
The French giants will arrive in the Irish capital two points ahead of their matchday rivals and come armed with the top points-scorer in the competition so far in Thomas Ramos.
Toulouse will not want to give up their unbeaten record in the competition this season either and Leinster will be out for revenge, having lost the reverse fixture by the slenderest of margins.
A 28-27 defeat for Leinster at Stade Ernest-Wallon helped put Toulouse in the driving seat and set up an enthralling encounter this time around.
In short, expect fireworks from two four-time winners.
— Leinster Rugby (@leinsterrugby) 9 January 2019
Ulster Rugby v Racing 92 (Saturday, January 12 15:15, Kingspan Stadium)
These two sides have only ever faced each other once in Europe – that was the reverse fixture in France, which the Top 14 side won 42-12.
Having won all of their fixtures in Europe this season, Racing present a tricky task for Ulster but the Irishmen are showing good form at home, having won nine of their last 10.
Ulster’s Jacob Stockdale is the only man in the competition to have scored in every game so far but Juan Imhoff can match his overall tally of four tries – so there could be tries aplenty.
🗣 Dwayne Peel: We’ll have to be more clinical this Saturday if we’re going to reverse October’s loss to Racing in Paris… pic.twitter.com/Pl6b9MMf5A
— Ulster Rugby (@UlsterRugby) 8 January 2019
Scarlets v Leicester Tigers (Saturday, January 12 17:30, Parc y Lanelli)
Qualification for Scarlets is nigh on impossible, having picked up only two points from their four European defeats this season.
However, the men in red will be hoping to draw momentum from their weekend win over Welsh rivals Dragons and put a spanner in the works for Leicester’s qualification hopes.
The Tigers have won only one game themselves – that was against Scarlets – but will be hoping for a victory of their own and a loss for Ulster to boost their slim chances.
— Scarlets Rugby (@scarlets_rugby) 5 January 2019
RC Toulon v Edinburgh Rugby (Saturday January 12 17:30, Stade Felix-Mayol)
Edinburgh basked in glory last time these two teams met as they put 40 points past the three-time winners.
In fact, Edinburgh have looked dangerous throughout the European campaign, winning three of their four games and sitting on top of the pool.
Meanwhile, good form in the Guinness PRO14 has seen them move up into second and they will be confident ahead of taking on French opposition.
However, Toulon have won 24 of their last 26 home games in the top flight and Edinburgh have only two wins on French soil from 19 attempts, so the odds aren’t stacked in their favour.
It doesn’t get much bigger… 💪🤩
— Edinburgh Rugby (@EdinburghRugby) 8 January 2019
Glasgow Warriors v Cardiff Blues (Sunday January 13 15:15, Scotstoun Stadium)
The fifth round of fixtures throws out one all-Guinness PRO14 clash and it will be between Glasgow Warriors and Cardiff Blues.
The two teams have experienced opposing degrees of fortune so far this season, with three wins for Glasgow and three defeats for Cardiff leaving a 10-point gulf between the two.
Glasgow have now won three on the spin but have never done it four times in a row in Europe – could this be the game that sees them achieve that feat?
— Glasgow Warriors (@GlasgowWarriors) 9 January 2019