Red Sox starter Clay Buchholz gathers himself after giving up a bases-loaded two-run single to Andre Ethier in the third inning that gave the Dodgers a 3-0 lead yesterday in Boston’s last exhibition game.

The Providence Journal / Bob Breidenbach

LOS ANGELES — Their two trips across the Pacific Ocean complete and their jet lag under control, the Red Sox might be excused for thinking that the most challenging part of their 2008 schedule is complete.

In fact, it has yet to really begin.

The long trips and overnight flights in which days magically disappeared — or reappeared — are over, but the Sox are about to start their most difficult April in a long time.

After the Sox complete what they started in Tokyo by finishing their series with the Oakland A’s on Wednesday, 21 of their next 34 games will come against teams that finished 2007 with .500 records or better.

“We’re going to get tested early — that’s for sure,” said manager Terry Francona as the team prepared to fly out last night.

After the set in Oakland, the Sox begin a stretch of 14 consecutive games against playoff contenders with in Toronto, three at home with Detroit, three at home with New York, two in Cleveland and two in New York.

The Sox then get something of a reprieve with Texas in town for four games before they host the Los Angeles Angels of Anaheim.

By April 22, then, the Sox will have met every other American League playoff team from a year ago — the Yankees (twice), the Indians and the Angels. The latter two, of course, were defeated by the Sox en route to their world championship.

Coming hard on the heels of the team’s journey to Japan and back, and their 19-day season-opening road trip, the first month figured to be demanding, anyway. But given the quality of the opposition, the Sox will be doubly challenged.

“But our guys aren’t complaining,” Francona said. “They’re pushing themselves — working out when maybe they don’t feel like it (after the trip to Japan). I trust them a lot to prepare the right way. Now, that doesn’t mean that we’re going to go 10-0 out of the gate. But it makes it a little easier, knowing the guys we have.”

A more balanced American League, with improvements from non-playoff teams such as Detroit and Seattle — will make easy stretches rare. It just so happens that the Sox are handed a tough stretch right away.

“It’s hard to avoid playing good teams in the American League,” general manager Theo Epstein said. “It’s almost like they’re everywhere. So we have to view it as an opportunity, rather than a problem.”

Recent history has shown the Red Sox to be fast starters. To find the last time they finished April with a losing record, one has to go all the way back to 1996, when the Sox went into May with a 7-19 mark and never recovered.

Then-manager Kevin Kennedy rather comically blamed the team’s poor start on traveling secretary Steve August for his role in scheduling too many road games in spring training, thus — in Kennedy’s mind — depriving the Sox of valuable preparation time.

Ever since, the Sox have run off 11 consecutive winning Aprils — with the occasional game in March. Tellingly, the team managed to get off to fantastic starts in both 2004 (15-6) and last year (16-8); both seasons culminated with World Series victories.

“We’ve been lucky to get off to good starts,” Epstein said. “If we play well this month, the results will take care of themselves. Playing good teams gets your attention in a hurry and can create some positive momentum” if you perform well.

Making matters more challenging is the fact the New York Yankees, the Sox’ arch-rvials, enjoy a cushier April. Beyond their two head-to-head series with the Sox and a four-game rematch with their ALDS opponent Cleveland, the Yankees will enjoy series with the Chicago White Sox (three games), the Kansas City Royals (three games) and the moribund Baltimore Orioles (three games).

Other than the games with the Sox themselves, the Yankees play just nine games in March and April against teams with winning records a season ago.

“I think, more than anything, we just need to get into the grind of our season,” Francona said, “and get into a routine. That’s the most important thing. I know who we’re playing (in April), but we’re not going to approach the games any differently.”

smcadam@projo.com

 One of the toughest stretches of the Red Sox’ season comes at the very start: