Twenty days may not be enough.

Alex Rodriguez has preached patience from the time his rehabilitation assignment began last Tuesday in Charleston, S.C., saying until he has 10 games under his belt and 25 at-bats, he won’t be able to make an accurate assessment of his progress.

But at this pace, the high-priced slugger with the surgically repaired left hip may not be ready by October.

He has produced just a single hit in nine at-bats and has failed to get the ball out of the infield in his other turns at the plate. Yesterday, he went 0-for-3 through five innings in Single-A Tampa’s 2-1 victory over Brevard County, a Brewers affiliate, at Space Coast Stadium, while curiously serving as the designated hitter.

Rodriguez lined out to shortstop in his first at-bat. He was buzzed — and soundly booed by the crowd thereafter — for the second straight day by a Brevard County starting pitcher. He popped up to first in the third and grounded into a double play in the sixth, jogging very lightly down the line to cap his fourth minor league game.

“You try to watch his at-bats and how hard he’s hitting the ball,” Yankees manager Joe Girardi said. “His contact is probably the most important thing, not necessarily if he went 2-for-3 or 3-for-4. You’d like to give him seven-to-eight days before you start to do that and see if you see an improvement.”

Since the lightning rod of a third baseman began playing in minor league games last Tuesday, starting the 20-day clock, he has appeared in games in four of the six days — there was a rainout mixed in — and has played third base three times, getting slotted as the DH yesterday. He is scheduled to be off today.

And, get this: Rodriguez doesn’t expect much to change.