TAMPA — On the sixth day, he pitched.

The Yankees have a plan to keep Masahiro Tanaka as healthy as possible, and that means giving him an extra day of rest now and during the season so he pitches every sixth day.

That’s a plan that makes a lot of sense and it should be carried through because of Tanaka’s small ligament tear in his right elbow. Extra rest won’t hurt the Yankees’ other pitchers either.

“It’s something we’d like to do,’’ one Yankees official told The Post on Friday of keeping the rotation on a six-day spin.

The extra workload Japanese pitchers face in MLB is one of the biggest wear-and-tear problems. The Yankees can use built-in off-days during the season to help set Tanaka’s schedule to give him those five days’ rest and then when an extra starter is needed they could reach down into the minor leagues.

Tanaka was magnificent in his two innings of work in his spring training debut Thursday against the Braves at Steinbrenner Field. Tanaka was able to drop the splitter on opposing hitters, fire a nasty fastball, and most importantly, expertly command all his pitches.

On Friday Tanaka said: “I feel better than last year.’’

That’s big.

That was in reference to where he was this time last year during spring training after he made the jump from Japan to the Yankees.

The key is to keep him feeling that way. To that end, Tanaka will pitch again Wednesday at Disney World, once again against the Braves, on five days’ rest. By doing so, Tanaka will gain another vital day of rest and will also avoid facing the Blue Jays on Tuesday.

The Yankees open up against the Blue Jays on April 6 at Yankee Stadium.

Several scouts on Thursday said the Yankees would best be served by giving Tanaka the extra day of rest. This is a most difficult transition in many ways.

The MLB baseball is bigger and more slippery than that used in Japan, so Japanese pitchers tend to squeeze the ball tighter, and that can be a problem.

Giving more rest between starts might help alleviate the situation. It just gives the arm another day to recover and, in theory, better protects the pitcher from injury.

The Yankees have been talking about going to a six-man rotation for a while. Part of the problem is they already lost their fifth starter, Chris Capuano, to a quad injury. Esmil Rogers, Bryan Mitchell, Adam Warren and Chase Whitley are in play for that spot now. But if it is a grab-and-go six-man rotation, reaching down into the minors whenever that starter is needed, that makes the situation a bit easier and more manageable.

The bottom line is the Yankees want to find an extra day of rest for Tanaka for as long as they can, just as they are doing now in spring training.

Too much is at stake here. If that extra rest enables Tanaka to pitch well and feel well — “better than last year’’ — it’s a win-win for the Yankees because Tanaka is their ace. If he is stronger during the season, can avoid Tommy John surgery and lead the Yankees to the postseason after a two-year absence, it’s all worth it.

The key is to keep Tanaka healthy and have him ready for the postseason. That means building more rest into his work week.

Yu Darvish, a proponent of the six-man rotation, is the latest pitcher from Japan who is heading toward Tommy John surgery. The Yankees need to do everything they can to keep Tanaka away from such a fate. This is a team with no room for error.

In his first game back, Tanaka showed what type of pitching force he can be for the Yankees. He lifted the spirits of the entire team by showing ace stuff.

Pitching coach Larry Rothschild said Tanaka will throw 45 pitches Wednesday, “maybe a little more’’ in his start against the Braves.

Getting the proper number of days of rest — five — is the number that really matters.