Nigel Davies’ men were beaten 19-14 in bitterly cold conditions in Stockport but still finished as winners of Pool 3.
A hat-trick of previous victories, including last week’s 27-19 home win over London Irish, meant a losing bonus point was always going to be enough to secure a spot in the last four regardless of results elsewhere.
Anything less would have opened the door for second-placed but Gloucester but the Cherry and Whites fell to defeat at Irish to ensure the Scarlets would have qualified even with a heavy reverse at Edgeley Park.
A well-taken try from prop Peter Edwards just after the half-hour and a brace of penalties from Dan Newton had the Scarlets looking good at the interval but Sale edged in front in the second period.
A 71st-minute strike from Stephen Jones, who was released from international duty earlier this week, kept the Scarlets in the hunt but the visitors couldn’t quite seal the win that would have led to a home semi-final.
A 14-point showing from former Blues fly-half Nick MacLeod proved the difference between the two sides as the Scarlets were handed a trip to 2010 winners Northampton on the second week in March.
Bath and Leicester were the other two teams to make it through, with the West Country outfit now due to host their perennial rivals at The Rec in just over a month’s time.
