Bristol Bears and Northampton Saints were no match for La Rochelle and Clermont in the European Challenge Cup quarter-finals.
There was a tense finish at Sixways Stadium as Harlequins won by just two points over Worcester Warriors in the European Challenge Cup.
The Challenge Cup was in danger of taking place without its defending champions, but Catalans Dragons will now participate in 2019.
Zebre led at half-time of their European Challenge Cup match at La Rochelle, but the hosts fought back in stunning fashion on Friday.
The Challenge Cup holders are not certain to compete in the competition this year after being asked to pay a £500,000 bond.
Tributes were paid to teenager Nicolas Chauvin before and after Stade Francais got the better of the Ospreys in Paris.
There were wins for the Ospreys, Sale Sharks and Clermont Auvergne in the European Challenge Cup on Saturday.
Barcelona's iconic stadium will host a rugby league fixture for the first time when Catalans Dragons face Wigan Warriors in May 2019.
Malaysian Premier League side UKM failed to take advantage of playing at home after being held to a 2-2 draw against Terengganu FC II (TFC II) in the first leg of the 2018 Challenge Cup final at the Shah Alam Stadium on Monday.
Catalans Dragons held off a late fightback from Warrington Wolves to become the first non-English team to lift the Challenge Cup.