Smith concentrates on the present
Sam Smith, who has agreed to join bottom-of-the-table Worcester in the summer, sunk his future club as Harlequins came from 13-0 down to narrowly deny the Warriors their first win of the season.
The 23-year-old winger scored a try and then created a second for debutant centre Harry Sloan as Quins, trailing until the 63rd minute, rallied to inflict a 16th successive Aviva Premiership defeat on Worcester.
Fly-half Ben Botica, stand-in for the injured Nick Evans, kicked Quins' other 11 points in the 21-20 success.
Worcester had opened up a 13-0 lead with a penalty from full-back Chris Pennell, a scintillating try from Samoan winger David Lemi and a conversion and penalty from fly-half Ryan Lamb, making his first start since his arrival from Leicester.
Pennell's late try and conversion earned them a losing bonus point.
Pennell kicked Worcester into a fourth-minute lead after Quins were penalised for a scrum infringement.
Lemi then beat three men in a run down the left before being hauled down as he cut inside.
Quins' former England winger Ugo Monye was sin-binned for illegally interfering at the breakdown but Pennell saw the resulting penalty rebound off a post.
Lamb took over the kicking duties when Harlequins strayed offside in the 18th minute but pulled a simple penalty wide.
The fly-half elected to go for touch rather than goal when Quins conceded their sixth penalty of the first half and the catch and drive at the line-out resulted in an easier kick when the home side dragged down Worcester's rolling maul near their line. This time Lamb made no mistake.
Lemi put Warriors further ahead with an opportunist try after 31 minutes
Snatching the ball from the base of a ruck, he spotted a gap in the Harlequins defence and darted through to score between the posts, leaving Lamb an easy conversion.
Worcester defended stoutly but failed to hold on to their 13-0 lead until half-time.
With a minute of the half left, they conceded a penalty at a scrum in front of their own posts and Botica opened his side's account.
Harlequins began the second half in a much more purposeful manner with scrum-half Karl Dickson racing 50 metres through the middle after taking a quick tap penalty.
Worcester conceded another penalty preventing Dickson from recycling the ball and Botica kicked his second penalty three minutes into the second half.
Botica put two penalties into touch as Quins continued to press and the next one saw Worcester's Argentinian replacement Leonardo Senatore, who had only come on for Sam Betty a minute earlier, sin-binned for collapsing a maul.
The depleted visitors were quickly stretched to breaking point when Dickson's long pass found Stuart, who forced his way over in the right-hand corner. But Botica missed what could have been an equalising conversion.
Another breakdown infringement saw Worcester fall behind for the first time when Botica kicked his third penalty after 63 miniutes.
Worcester fell further behind when Smith linked up on the left to send 2013 IRB Junior World Cup winner Sloan in for his try.
Worcester lost Senatore with a suspected dislocated shoulder but fought to the end and salvaged a losing bonus point when Pennell cut through the Harlequins defence for a 75th-minute try, which he converted.