Guernsey FC boss Tony Vance says protecting striker Ross Allen was the reason his side nearly gave up a 3-0 lead at Bookham.
Sam Cochrane, Luke Winch and Joe Alvarez all scored in the first period to put Guernsey in command.
But 21-goal Allen was taken off after suffering a knock and Bookham fought back strongly to finish the game 3-2.
"We didn't have any natural forwards left and had to change our shape," Vance told BBC Guernsey.
"We had to move people around and that, in combination with them having a real go as they had nothing to lose, kind of allowed them back into it," Vance added.
The victory enabled Guernsey to increase their lead to five points at the top of the Combined Counties League Division One after rivals Bedfont Sports were held to a 2-2 draw by third-placed Eversley.
"To come away with three points at the end of the day was what we were asking of the lads and I'm happy," Vance continued.
"We were worthy winners in the end but it got a little too close for comfort," he added.