Paris - Harlequins shrugged off the Joe Marler controversy to beat struggling Premiership rivals London Irish 38-30 on Saturday and reach the European Challenge Cup semi-finals.
Marler was serving the first game of a two-match ban imposed by World Rugby for his 'gypsy boy' remark aimed at Wales's Samson Lee in the Six Nations.
Mark Lambert replaced Marler but it was England scrumhalf Danny Care who starred with a hat-trick of tries for the three-time Challenge Cup champions.
Flanker Luke Wallace grabbed two tries as Quins hit back from 30-18 down to score 20 unanswered points in the last half an hour.
Fergus Mulchrone, Brendan McKibbin and Sean Maitland scored tries for London Irish who are rock bottom in the English Premiership.
Quins will face Grenoble in the semi-finals after the French side overcame a 19-13 deficit at the break to edge Connacht in a 33-32 thriller secured by a 75th-minute drop goal from Jonathan Wisniewski.
The flyhalf contributed 23 points courtesy of his one of his team's three tries, three conversions, three penalties and his late, decisive drop.
Newport Gwent Dragons reached the semi-finals by knocking out holders Gloucester 23-21 with the winning try coming just four minutes from time.
Replacement scrumhalf Charlie Davies grabbed the decisive score to overturn a 21-18 deficit to add to five penalties from flyhalf Dorian Jones and one from fullback Carl Meyer.
Ben Morgan and Stevie McColl scored tries for Gloucester, with skipper Greig Laidlaw kicking three penalties and a conversion.
Victory for the Dragons gave them a semi-final spot against French Top 14 side Montpellier.
"By winning away, we've got the monkey off our backs," said Newport coach Kingsley Jones after the Welsh region picked up only their second away win of the season.
Dragons were rewarded for their positive approach when they chose to go for the drive from a line-out instead of kicking a penalty to draw level.
"It was a big call from our skipper (Lewis Evans) but we came here to win and we didn't want to settle for a draw," said try-scorer Davies.
"At first they defended the line-out well, even though we had put all our backs in. I then heard a call to go to the blind side and I used my size to get over.
"No-one backed us to win here but I'm elated to score the winning try and I'm very happy for the team as a whole."
On Friday, Montpellier reached their first European semi-final when they defeated hosts Sale 25-19.
The reliable boot of Benoit Paillaugue proved crucial for Montpellier as he kicked five second half penalties to help turn round an 11-10 half-time deficit.
Former England flyhalf Danny Cipriani kicked two first half penalties to add to winger Tom Brady's try.
Montpellier, on a run of six successive wins in the French Top 14, had also grabbed a first period try through Paul Willemse.
But Paillaugue's deadly boot was enough for Montpellier despite a late try for Sam James.