BOSTON -- The results of an initial exam suggested Tuesday that the Red Sox had dodged a bullet in terms of David Ortiz and his sore Achilles. But it still remains to be seen whether this proves to be the shot that ultimately kills them.

After Boston’s designated hitter came up lame while circling the bases on Adrian Gonzalez’s eighth-inning homer on Monday, an MRI showed no structural damage or tearing in his heel, however Ortiz arrived to Fenway Park in a walking boot Tuesday and after saying “(Tuesday) was worse than (Monday) when it comes down to soreness,” he’ll head for a second opinion today.

While awaiting that diagnosis he was not placed on the disabled list, but he will likely miss a week at minimum — and with the precarious position injuries and inconsistency have put the Sox to this point, even an absence of that length could be long enough to hurt them, considering the caliber of the upcoming competition. And anything longer could be downright dooming.

One school of thought suggests that if Ortiz was to go down, now would be as good a time as any this year, considering the club finally has Jacoby Ellsbury and Carl Crawford back in the outfield, and Dustin Pedroia is on track to return to second baseman on Thursday. To put it in Larry Lucchino’s lexicon, it’s now as close to the “varsity” lineup as Bobby Valentine has had at any point in his first season.

But Ortiz entered Tuesday as Boston’s leader in runs, hits, homers, RBIs, walks (he had more than any two teammates combined), batting average, on-base percentage, slugging percentage, on-base plus slugging and total bases. Furthermore, he was the American League leader in runs scored, times on base, OPS, and he joined Yankees second baseman Robinson Cano as the only two hitters ranked among the AL’s top 10 in all three Triple Crown categories.

And this is not a good time for those contributions to go missing. If Ortiz is eventually added to the DL, the earliest he could return is August 1 — before which the Red Sox will face the White Sox, Blue Jays, Rangers, Yankees and Tigers.

Not only does that gauntlet include the leaders of all three AL divisions, as well as a Detroit team that began Tuesday in playoff position, but those clubs signify five of the six highest-scoring offenses in the league. With a below-average pitching staff, the Sox figure to need every run they can get against those attacks — and being forced to fight that battle without their most valuable bat will at the very least make things more difficult during a stretch they were hoping would help build momentum heading toward the trade deadline.

If Ortiz was healthy, the Sox would have entered all of those matchups with an advantage at the DH position — and, with that in mind, Valentine says he doesn’t expect any one player to replace Big Papi.

“We can rotate guys through if we want,” Valentine said. “I don’t see one person sticking out as someone we are going to put there and say, ‘He’s replacing David Ortiz as the designated hitter.’ You don’t do that. I think we will get some contributions from people that will help us score runs.”

Tuesday night that person was Daniel Nava. Don’t be surprised to see Ellsbury, Crawford or Pedroia in that role as they continue coming back from their injuries. Gonzalez could do it if his back needs a break, or it could be a way to fit Cody Ross or potential call-up Ryan Lavarnway into the lineup from time to time.

But no matter where they might be playing, the same is true for all of those players. Even if they’re not replacing Ortiz as the designated hitter, those guys need to collectively find a way to somehow, some way replace the monstrous numbers that Ortiz brings to the lineup.

Because if they don’t, the Red Sox may have trouble surviving the next couple weeks.

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VALENTINE announced before the game that his team would go back to a five-man rotation, meaning Franklin Morales would join the bullpen as a second left-hander — and effectively giving a vote of confidence to Aaron Cook and his 3.34 earned run average.

After throwing seven innings without allowing an earned run on Monday, Cook has struck out only two batters in 29 2/3 innings this season — while Morales has 53 whiffs in 51 1/3. There’s no question Morales has better “stuff,” but clearly the Red Sox believe opponents’ .212 average against Cook on balls on play in his past four starts is more a product of Cook’s sinker than pure luck, and feel comfortable he can fill the role more capably than Morales in the immediate future.

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WHEN ex-teammate Kevin Youkilis blasted a three-run homer against him in the fourth inning Tuesday night, Jon Lester had allowed at least six earned runs in a start for the third time this season. That’s more than he had in the 2008, ’09 or ’11 seasons, and leaves him just one shy of the career-worst four such outings he experienced in 2010.

When Junichi Tazawa replaced Lester before the next frame, it marked the third time this season the 28-year-old lefty has failed to reach the fifth. He did that as many times all of last year.

Dave D’Onofrio covers the Red Sox for the New Hampshire Union Leader and Sunday News. His e-mail address is ddonof13@gmail.com.