The Red Sox remain deeply involved to bring free agent pitcher Jon Lester back to Fenway Park. But by no means have they placed all their eggs in his basket.

They can’t afford to.

The chance of Lester simply saying no to the Red Sox or another team pushing its offer beyond the team’s comfort zone is a real one, no matter how far principal owner John Henry is willing to bust through the luxury tax threshold.

The Sox have contingency plans without Lester, and with one exception, their solution would be a trade. The two biggest backup plans are Cole Hamels of the Phillies and Johnny Cueto of the Reds.

Currently, the Phillies are considered most eager to discuss dealing Hamels, who is signed through 2018 but would likely require his 2019 option year to be picked up in any deal. According to one source, the Phillies’ current asking price for Hamels is too high for anyone’s liking but that it may drop soon.

That likely means that in addition to dealing away their biggest trade chip, outfielder Yoenis Cespedes, the Sox may find the Phillies wanting at least two of their young players. That could mean pitching prospect Henry Owens and outfielder Mookie Betts or even shortstop Xander Bogaerts, a price that for now, with Lester still on the board, is way too high.

The Reds would prefer to deal Mat Latos or Mike Leake before Cueto, their best pitcher who finished second in NL Cy Young voting this season. There certainly have been loud whispers of late that the Reds like Cespedes. But it would likely take Cespedes plus a very good prospect to land Cueto, even though he is a free agent after 2015. Latos or Leake could be had for a much lesser price but neither is considered a Lester fallback.

Below Cueto and Hamels, there is a second-tier of starters in trade discussions who could develop into an ace or at least lock down the vacant No. 2 spot in the Sox rotation.

With so many rumors swirling, among the most believable, as far as the Red Sox are concerned, include Rick Porcello of the Tigers, Tyson Ross and Ian Kennedy of the Padres, the A’s Jeff Samardzija, Hisashi Iwakuma of the Mariners, Jordan Zimmermann of the Nationals and the Mets’ Zack Wheeler and Noah Syndergaard.

That’s a long list, and there are undoubtedly other teams with an interest in Cespedes.

Nobody should be shocked to learn that the Red Sox will have to kick the tires on Max Scherzer if they miss on Lester. This is the biggest longshot on the board. Most expect Scherzer, who has less mileage than Lester, to land a bigger deal than the six- to seven-year deal worth at least $22 million to $25 million that Lester is going to get.

But if the Sox strike out with Lester, they pretty much have to discuss the Detroit Tigers righthander, if for no other reason than to drive up his price on the Yankees, who are expected to get in the chase.

JOSH DONALDSON lauded his new destination during a Saturday conference call.

“Toronto is a great place, a great city,” the All-Star third baseman said. “Every time I’ve been there it’s been very beautiful.”

Now he will try to see what he can do about the ballpark. The Blue Jays went 83-79 last season and finished out of the playoffs for a 21st straight year, the longest active drought in baseball.

“I definitely think the elements are there to win,” he said.

The Blue Jays acquired Donaldson from Oakland for infielder Brett Lawrie, left-hander Sean Nolin, right-hander Kendall Graveman and minor league shortstop Franklin Barreto.