Smith's Quins eliminate La Rochelle, Bordeaux and Glasgow secure top seeds
Earlier, Louis Bielle-Biarrey scored an opportunistic late try to complete his hat-trick and secure a 27-15 victory for Bordeaux-Begles at Bristol that earned them the top seeding for the knock-outs.
Glasgow made sure they would also enjoy home advantage all the way to the semi-finals with a dominant 28-3 victory over Saracens in Pool 1.
La Rochelle needed only a losing bonus point to book their place in the last 16 at fellow two-time winners Leicester's expense but were undone by a late Quins flourish.