Wasps back-up kicker John Ufton failed with a last-kick conversion attempt as Harlequins won the London derby by a single point on Sunday.

Harlequins' John Schuster collected four penalties, a conversion and the drop kick, while Wasps' kickers crucially missed when the result was in the balance.

Ufton's almost impossible kick with his left foot from the left touchline was far more difficult than Kenny Logan's chances just after the hour with the score poised at 16-19.

Logan hooked from halfway out each time and when Schuster landed a drop kick in the 76 minute Quins led 22-16.

Wasp's needed a converted try, but all they managed was sub Nick Greenstock's corner try deep into injury time.

Quins made it four wins in a row and will be threatening the big boys of the championship after floundering around the foot of the table until late last month.

Harlequins scored the opening try through Scottish centre David Officer in the 13th minute with Schuster converting.

But Wasps took charge towards half-time with Logan taking a penalty and converting a try by Laurence Scrase that was set up by Rob Henderson.

Logan added another penalty and Wasps looked a good bet at 16-10 in the 35th minute. But they repeatedly conceded penalties and by half-time Schuster had levelled with a couple of kicks at 16-16.

By the hour Schuster's fourth penalty had taken Harlequins to 19-16 and after Logan's failures Schuster's set-up drop kick gave the match a gripping climax.