Bognor's George Bingham managed to snuff out Horndean's 1-0 lead with a belter of a goal in the 78th minute in a spirited display from both sides at Five Heads Park.
Bognor elected to play up the slope as the teams kicked off in the sunshine, and Michael Birmingham's Horndean, as expected, gave Bognor a very stiff test.
Jimmy Muitt struck a chance well over the crossbar on the turn early on before Rocks keeper Charlie Searle made a confident save at the other end.
Muitt scraped the top of the bar with his shot on 11 minutes, then James Crane cleared a chance off the Bognor line.
Ex-Rock Dan Sackman was late in the tackle on Dan Smith near the touchline and went into the book on 17 minutes.
Likely loan signing from Pompey Joe Dandy got on the end of a corner by Muitt but his header was straight at the goalkeeper. Another Deans strike was hit low at goal which was saved by Searle on 34 minutes after a partially cleared ball fell to him.
Stuart Green set up Crane to force a decent save from the goalkeeper. Muitt smashed one wide from a tight angle moments later.
Crane had to come off after he complained of double vision following the earlier headed block on the line and he was replaced by Bingham.
The Rocks were caught out on the break and Bingham was beaten to allow Jackson in to slot a shot beyond Searle on 44 minutes.
Smith was set through on goal but one on one with the goalkeeper he was denied. HT 1-0
Another Pompey loan recruit, Petar Durin, came on in goal for Bognor as the second half kicked off. Tommy Leigh, a new signing from Baffins Milton Rovers, replaced Dandy. Emmett Dunn came on for Tuck and Tommy Scutt replaced Freddie Read on 52 minutes.
Green hit a low shot off a defender on the rebound on 56 minutes. Sackman tripped Ashton Leigh to give the Rocks a penalty but Thomas dived to his left to save Muitt's kick.
Josh McCormick and Dan Simmonds came on for Bognor on 64 minutes for Smith and Muitt. Simmonds pounced on the right to ping the ball in towards the back post but it was just ahead of McCormick.
Whyte sent the ball wide to Green, who won a corner. Green's corner picked out Bingham who hit it sweetly from 25 yards and into the net to level the score on 78 minutes. A great strike.
Tommy Leigh forced a save from the Deans keeper before Green hit the rebound over the bar.
Simmonds got on the end of a curling Dunn cross but the goalkeeper was brave to get in the way of him./
This game proved a great workout for both sets of players. Match fitness is improving for the Rocks and players are getting some momentum as the Isthmian Premier season approaches. All 18 players got some much-needed game time here.
The Rocks take on Chichester City at Lancing’s Culver Road on Tuesday, July 30, at 7.30pm in the Sussex Community Shield.
Rocks: Searle (Durin 45), Crane (Bingham 34) , A Leigh, Tuck (Dunn 52), Dandy (T Leigh 45), Wood, Whyte, Read (Scutt 52), Smith (Simmonds 64), Muitt (McCormick 64), Green.