Horsham made it two away wins in three days to continue their fine festive form and complete the double over Tooting & Mitcham.
Tony Nwachukwu and Laurent Hamici traded penalties before Scott Tipper headed Horsham back into the lead on the stroke of half time.
The Hornets rode their luck at times in the second half, Hamici striking the post and goalkeeper Michael Hunter with some crucial saves before Charlie Farmer sealed a 3-1 win and only Horsham’s third league victory on their travels all season.
Horsham hadn’t lost at Tooting since 1999, although the game at Imperial Fields only went ahead thanks to a vast amount of water being pumped from the pitch.
Although the pitch was heavy there was none of the wind and rain at Worthing on Boxing Day and as expected with two teams in similar positions in Ryman South it was a close contest throughout.
Both sides had threatened to open the scoring before Nwachukwu went down under the challenge of Sofiane Fadel and the referee immediately pointed to the spot. The young forward picked himself up to send Darren Behcet the wrong way and make it two goals in two games.
Horsham’s lead lasted ten minutes before Scott Harris’s clumsy challenge on Hamici gave the Terrors striker the chance to level from the spot and he made no mistake to make it 1-1.
The hosts finished the half strongly, although in stoppage time Horsham were awarded a free kick on the left, and when Scott Harris picked out Farmer at the far post he won a good header back across goal for Tipper to nod the visitors into a 2-1 lead at the break.
The Terrors spent most of the second half pushing for an equaliser and came close on a number of occasions.
Hamici struck a post and Hornets stopper Hunter denied Tyrone Berry on the rebound before Hamici blazed over.
Carl Wilson-Davis flicked a volley just wide and Hunter made saves from Hamici - who was particularly wasteful in front of goal - and sub Bamoussa Cisse to keep the visitors just ahead.
And right on 90 minutes Horsham sealed all the points when Tipper wriggled past a challenge on the right and found sub Aaron Scott to drill a ball to the back post for Farmer to slam home from close range.
The result matched the 3-1 scoreline when the sides met earlier in the season at Gorings Mead, Horsham’s first win of the season, and six points in three days has lifted Simon Colbran’s side up to 11th in the Ryman South table.