Boss John Gregory admitted he made a "big mistake" in his tactics as Crawley had to fight back to earn a 2-2 draw at home to Preston.
Gregory opted for a 3-5-2 formation but the experiment backfired as Preston raced into a 2-0 lead inside 16 minutes through goals form Paul Huntington and Josh Brownhill.
The Reds boss quickly reverted to a more familiar 4-4-2 and it sparked a comeback, although they had to wait until the 65th minute for Joe Walsh to pull a goal back.
Crawley's second half revival looked to be in vain as Joe Walsh hit a post and Alexander had a goal ruled out for offside but the veteran striker grabbed the equaliser in the first minute of stoppage time from a corner.
Gregory said: "I made a big mistake in how I started off in our shape and formation. I thought we were capable of playing that way it wasn't going to plan.
"I take total responsibility for the first 20 minutes and giving them a two-goal start. They weren't comfortable with what I asked them to do so I changed it.
"We were a lot better going to 4-4-2 and from the first minute I brought on Andy Drury (for James Hurst) and went to a back four we took over the game.
"The second half was one-way traffic. With the pressure and possession we had I thought we might go on and win it."
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