Adam Sargent and Jonno Melia came into the side in place of Russ Tanner and Ashley Jarvis as United looked for a reponse to Saturday's FA Cup defeat to Hastings United.
The game started at a high tempo with Jamie Hillwood fizzing a cross along the United six yard box within the first five minute, before Jason Taylor did the samet the other end, but Taylor's cross was just too quick for an outstreched Paul Rogers.
The home side took the lead with ten minutes played as the ball was rolled to Dan Jaques who looped an effort past Sargent, as United went behind for the first time in a league fixture this season.
The goal appeared to kick United into life, with Taylor and Lucas Mann both coming close to scoring.
After a five minute spell of prolonged pressure on Hassocks, United were level and it was Taylor who got it.
The jet heeled winger cut in from wide amd hit an effort under Hassocks 'keeper Josh Green from 15 yards.
On 35 minutes the dimension of the game changed as Hassocks were reduced to ten men when Ian Simpson was dismissed for a professional foul after dragging Taylor down inside the six yard box following a parried effort from Wes Tate.
After a two minute delay, Tate stepped up and confidently slotted the penalty home to give United the lead
Two minutes later, the ten men drew level as Ellis Common found space to beat Andy Corrigan and fire across Sargent, his effort going in off the far post.
Almost immediately, United hit back and regained the lead when Lucas Mann bundled home a loose ball inside the six yard box.
With less than five minutes played in the second half, Hassocks drew level once again as Aaron Czech slid the ball under Sargent folling a low ball into the area from the left wing.
Mann was twice denied a second goal, firstly after his smart turn and shot was saved by Green, before seeing a header tipped onto the post.
Ben Dartnall came a posts width away from scoring when his curling effort rebounded off the far post after Rogers had dispossessed Jaqueson the touchline.
With five minutes to play, Sargent had to get down quickly to save from Hillwood, but it was Green who ensured a share of the spoils for Hassocks as he again denied Mann, this time with a full length dive to stop Mann's header in time added on as United dropped their first league points of the season.