Worcester secured a scrappy 25-19 victory over Nottingham in a bruising Championship play-off encounter to go nine points clear at the top of Pool A.
Wing Marcel Garvey and hooker Chris Fortey scored first-half tries as the Warriors took a 15-6 lead at the break.
Miles Benjamin took his tally to seven in three play-off games with an early strike in the second half.
Former Worcester player Tim Streather scored an injury-time try to secure a losing bonus point for Nottingham.
The league winners and Pool A leaders took the lead through an Andy Goode penalty and an unconverted Marcel Garvey try.
But Glenn Delaney's side replied instantly, scoring straight from the restart by earning a penalty that James Arlidge successfully kicked.
Then, after a second Garvey try was disallowed for a knock-on over the line, hooker Chris Fortey crossed the line for Warriors and this time Goode converted.
A penalty either side of half-time put Nottingham within six points, and took Arlidge over the 300-point mark for the season.
It was a physical contest from the start, and when Nottingham's Phil Eggleshaw and Worcester's James Collins were grounded in separate collisions, the game stopped for nearly 10 minutes.
Eggleshaw managed to hobble off, but unfortunately Collins was stretchered off in a neck brace.
Following a brief threat from Nottingham to score a try and take the lead, a Miles Benjamin converted try and a penalty apiece put Worcester 13 points ahead.
And when Ben Buxton collected a yellow card with eight minutes left, it seemed unlikely that Nottingham would get anything out of the game, but Tim Streather's late try and a coolly converted kick ensured a vital bonus point for Delaney's side.
Warriors head coach Richard Hill told BBC Hereford and Worcester: "That game was what cup rugby is all about and I have been telling the team all season.
"We have all enjoyed ourselves playing some beautiful rugby, but when it comes to the semi-final that is what you are going to get.
"We had overwhelming possession, overwhelming territory and I am very angry that we didn't get the four tries.
"We had enough possession and territory to get six or seven and we have only got three. We will want to put that right next week."
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