London - Highly-regarded flyhalf Marcus Smith showed the qualities which have earned rave reviews with 14 points as Harlequins ended Wasps' record 20-win streak at home with a 24-21 victory on Sunday.
Wasps, suffering only their second Premiership defeat in their last six matches, had only themselves to blame as veteran England back row forward James Haskell and mercurial flyhalf Danny Cipriani were sin-binned.
The points from Philippines-born Smith, and tries by Marland Yarde and Charlie Walker, edged the match the visitors way.
However, Wasps, losing finalists last season to Exeter, did move into second spot thanks to a bonus point.
They too scored two tries through the prolific Christian Wade and Tom Cruse -- Cipriani contributing 11 points with the boot.
For Harlequins, who moved into fifth spot, it was their first away win since beating Gloucester in March.
Exter top the table by a point from Wasps after three matches having defeated Worcester Warriors 41-10 on Friday.