Before his last “opener’’ on Saturday night in Anaheim against the Angels, A’s right-handed reliever Liam Hendriks sat patiently at his locker reading a book.

You can expect the same calm pregame approach from Hendriks if, as expected, he is the opener for the A’s against the Yankees on Wednesday night in the AL wild-card game at Yankee Stadium.

Considering he was designated for assignment in late June, this is quite the comeback story.

The books that the Australian prefers deal in historical fiction. The one he is reading currently is “about the French invading England during 1066,’’ Hendriks said.

Hendriks, 29, posted an 0-1 mark with a 4.13 ERA this season, but as an opener he has been the real deal for that one inning and he will have to match up against the top of the Yankees lineup as the A’s are expected to go with a full bullpen game.

When he was designated by the A’s, his ERA was 7.36 and opponents were hitting .362 against him.

In his last seven openers, Hendriks is unscored upon and he’s given up just four hits and two walks.

But this is a wild-card game, win or go home, and all eyes will be on hm.

“There’s definitely going to be a lot more scrutiny on it,’’ Hendricks said. “It’s one of those things if it doesn’t work, it’s going to be the reason, whereas if it does work, it would be the reason as well. Everything is going to be amplified.’’

With all the starting pitching injuries the A’s have had, using an opener is the way to go. It’s not as if they have an ace just sitting there. As A’s vice president of baseball operations Billy Beane told the San Francisco Chronicle about a bullpen game at this point: “You pull out all stops to win that game and throw all tradition out the window. It’s a cage match with no rules.’’

So, to prepare for this battle and to just relax Hendriks reads about the Battle of Hastings. It’s all about winning the war.

“At the end of the day as long as you get 27 outs, that’s all that matters,’’ Hendriks said. “If we’re able to get all 27, we can extend this thing a little bit longer. It’s another game. The game is the same, there is just going to be a lot more eyes on it. It’s always fun to be at the start of something. If you pitch in a game like this, the biggest thing is to taking the emotions out of it.’’

Hendriks can rip through a book in a couple of days. “I’ll sit down there for a couple of hours reading,’’ he said of his plan. “It calms me down a little bit.’’

Open a book before being the opener.