Moneys stormed back from 0-2 down to win 3-2 with goals from Ryan Pennery, Chad Cornwell and Callum Laycock.
The Royals had won their previous 15 Premier Division fixtures at the On-Site Group Stadium this season.
Moneys’ victory allowed Horndean to cut Portchester’s lead to seven points, with the Deans still having two games in hand.
Pictures by Nathan Lipsham
. Jack Chandler celebrates a famous win for Moneyfields
Jack Chandler celebrates a famous win for Moneyfields. Picture by Nathan Lipsham Photo: -
. Moneyfields boss Glenn Turnbull celebrates his side's stunning win
Moneyfields boss Glenn Turnbull celebrates his side's stunning win. Picture by Nathan Lipsham Photo: -
. Portcehester's Scott Jones, right.
Portcehester's Scott Jones, right. Picture by Nathan Lipsham Photo: Nathan Lipsham
. Portcehester's Brett Pitman, right
Portcehester's Scott Jones, right. Picture by Nathan Lipsham Photo: Nathan Lipsham
. Moneyfields' Jack Lee keeps a close eye on Brett Pitman
Moneyfields' Jack Lee keeps a close eye on Brett Pitman. Picture by Nathan Lipsham Photo: Nathan Lipsham
. Moneyfields defend a corner
Moneyfields defend a corner. Picture by Nathan Lipsham Photo: Nathan Lipsham
1. Moneyfields boss Glenn Turnbull celebrates his side's stunning win
Moneyfields boss Glenn Turnbull celebrates his side's stunning win. Picture by Nathan Lipsham Photo: -
2. Portcehester's Scott Jones, right.
Portcehester's Scott Jones, right. Picture by Nathan Lipsham Photo: Nathan Lipsham
3. Portcehester's Brett Pitman, right
Portcehester's Scott Jones, right. Picture by Nathan Lipsham Photo: Nathan Lipsham
4. Moneyfields' Jack Lee keeps a close eye on Brett Pitman
Moneyfields' Jack Lee keeps a close eye on Brett Pitman. Picture by Nathan Lipsham Photo: Nathan Lipsham