Sussex Seconds failed to make it back-to-back wins in the Championship after they were beaten by Surrey on Wednesday.
Mike Yardy's young side travelled to LSE New Malden full of confidence, but Matt Dunn's superb second innings figures of 7-31 saw Sussex lose by 341 runs.
After being put into bat on day one, Surrey opener Nick Welch was in imperious form during the morning session, and with the help of Chris Green, the hosts were 136-2 at lunch and looked to push on in the second session.
Abi Sakande eventually dismissed Welch for 149, before Green fell after tea for an equally excellent 155 off the bowling of academy star Will Sheffield.
Sam Hall added some important late runs at the end of innings, before Sheffield claimed his third wicket of the day and Surrey were all out for 428.
After impressing with the bat, Surrey were also dangerous with the ball in a tricky 11 over spell at the end of the first day, with captain Laurie Evans bowled for eight and Sussex finishing on 31-1.
On day two, Yardy's side had to work hard for runs against more accurate bowling from the Surrey attack, but Tom Clark scored 53 and Aneesh Kapil scored 70 to build a total of 245 all out, with help from Brandon Gilmour (28).
Surrey then declared on 212-4 at the end of their seconds innings, with Sakande dismissing the star of day one, Nick Welch, for 22 and Arun Harinath for 9, with Will Collard and Sheffield claiming the wickets of Nathan Tilley and Angus Dahl.
The hosts started the final day needing 10 wickets, while Sussex needed 395 to win, but Dunn's excellent performance saw Surrey ease over the line and bowl their opponents out for 81 inside 29 overs.
Delray Rawlins was Sussex's best performer on the final day, but it wasn't enough as Dunn dismissed him for 38, before clearing the tail in emphatic fashion.
A full scorecard from the match can be downloaded below.