FORT MYERS, Fla. — Sometime this week — maybe today, maybe tomorrow — Manny Ramirez is expected to arrive for the start of his eighth season with Red Sox.

It could also be his last.

When Ramirez checks into camp, will it mark the unofficial beginning of the end?

The landmark eight-year, $160-million contract signed with the Sox after the 2000 season is complete when this season is over. The Red Sox have options for both 2009 and 2010, each worth $20 million and the team must make its determination no later than the first week of November prior to each season.

Expect that they will take all the time they need, because this won’t be an easy decision.

Ramirez has performed at an extraordinary level for the Sox. Among Red Sox players in history with a minimum of 3,000 plate appearances, Ramirez currently ranks fourth in slugging percentage and OPS (on-base plus slugging percentage), fifth in on-base percentage and seventh in batting average.

In five of his first seven seasons with the Sox, Ramirez has hit .300 or better — and never less than .292. In all but one year, he hit no fewer than 30 homers and knocked in at least 100 runs.

But Ramirez will turn 36 at the end of May and he is coming off the worst of seven seasons in Boston. He hit just 20 homers and collected only 88 RBI. He missed 24 games from the end of August until the final week of the season.

His torrid postseason (.348 average, 4 homers, 16 RBI in 14 playoff and World Series contests) ended his 2007 with a flourish, but there are questions:

Was Ramirez’s power drop-off — his .493 slugging percentage was the lowest figure of his career — an aberration or a sign of impending decline?

Will Ramirez still be worth — relatively speaking — $20 million annually at age 37 (2009) and 38 (2010)?

Do the Red Sox have other viable (and cheaper) run-producing options to replace him?

There seems little doubt that Ramirez senses something may be at stake this spring. He journeyed to Arizona to train at the renowned Athletes’ Performance Institute (API) this winter, a first. Tampa Bay Rays outfielder Carl Crawford, who trained with Ramirez, came away in awe of Ramirez’s commitment this offseason.

“Manny might have a big year this year — watch out for that,” Crawford told the St. Petersburg Times. “He’s working hard. It surprised me. Something must be going on.”

Perhaps Ramirez is merely intensifying his conditioning as many players do in deference to advancing age. Perhaps, too, he’s trying to make a statement to the Sox — or perspective bidders next fall, should the Sox pass on his option — about his readiness to continue producing at an elite level.

His deal, signed at the beginning of this decade, has not often been surpassed. Among current position players, only Alex Rodriguez — whose first mega-deal was signed the same offseason as Ramirez’s — makes more in average annual value (AAV). Rodriguez’s recent extension with the Yankees is worth an average of $27.5 million per season.

But after Rodriguez, the next largest position player contracts since Ramirez joined the Red Sox are all below his present deal’s worth: Andruw Jones ($18.1 million AAV); Torii Hunter, Ichiro and Vernon Wells (all $18 million AAV).

That Rodriguez is the only position players to have passed him in the last seven years shouldn’t come as surprise. A-Rod is the only active player with more RBI from 1998 through last season (1,275 to Ramirez’s 1,232), and if Sammy Sosa and Barry Bonds stay retired, he’ll be the only player with more homers than Ramirez in that same span (454 to 381).

But the Red Sox aren’t about to get sentimental for $20 — or $40 — million. If they pick up one or both of his options, it will be because they think he’s a good investment going forward, not looking back.

That’s why they intend to use all of this year to monitor his performance. In this case, time equals money — the more the Sox have of the former, the better they can evaluate the question of the latter.

Should the Sox pass, their remaining options could be limited. Next year’s free-agent class isn’t much better than the last one, with Mark Teixeira the only run-producer in his prime. Problem is, the Sox would have to do something with Kevin Youkilis to make room for Teixeira.

Certainly, despite a restocked inventory of prospects, there are no power hitters in the immediate pipeline. According to scouts and Baseball America, the Sox’ best power prospect is first baseman Lars Anderson, who won’t turn 21 until September and has yet to play above high Single A.

Ordinarily, Ramirez’s appearance in spring training is the subject of great conjecture and speculation. It’s more than a little ironic that this spring, the question isn’t when he’s going to arrive, but rather, how much longer he’s going to stay.

smcadam@projo.com