Crawley Town extended their unbeaten record in pre-season thanks to two goals by Panutche Camara against his former club.
Enzio Boldewijn and Matt Harrold completed the scoring away to the Bostik League Premier Division side in south east London.
Boldewijn gave Reds the lead in only the third minute with an assured finish after Billy Clifford won the ball in the opposing penalty area.
Substitute Camara scored against his former club after he replaced the injured Aryan Tajbakhsh and took advantage of a poor back-pass before netting Crawley’s 29th minute second goal.
Dulwich pulled a goal back seconds later when keeper Glenn Morris missed a cross and Dumebi Dumaka headed home.
The two teams went into half-time level at 2-2 after Dumaka evaded the visitors’ challenges and blasted in Dulwich’s second goal.
Head coach Harry Kewell played a completely different XI for the second half.
Jordan Roberts struck the bar with a spectacular volley, while Harrold was denied on the rebound by keeper Preston Edwards.
Reds regained the lead eight minutes into the second half when Moussa Sanoh’s initial shot was parried as far as Harrold who played a square ball to Camara who made it 3-2.
At the other end former Crawley player Gavin Tomlin forced Josh Lelan to clear off the goalline.
Reds increased the lead to 4-2 with five minutes to go when Sanoh went on a run and crossed to Harrold to score put away his sixth goal of pre-season.
There was still time for both sides to have one more attempt on goal with Mersin denying Dulwich’s Gustavo Ferraz and Edwards kept out attempts by both Sanoh and Harrold.
REDS: Morris, Tajbakhsh (Camara 11), Yorwerth, McNerney, Blackman, Djalo, Payne, Clifford, Lewis, Cox, Boldewijn
Subs: Mersin, Young, Lelan, Evina, Randall, Bulman, Sanoh, Roberts, Harrold