OAKLAND, Calif. – Leaving the comforts of home for the rigors of the road, the Red Sox got an entirely predictable result last night.

While the Sox have been almost unbeatable at Fenway Park, sweeping their recent seven-game homestand and posting a 21-5 mark at home this season, the road has not been nearly so kind.

Opening a 10-game trek last night, the Sox stumbled badly, thumped by the Oakland A’s, 8-3, for their fifth straight road loss and seventh setback in their last nine tries away from home.

``We don’t think about it,’’ said second baseman Dustin Pedroia, who had a solo homer in the fourth. ``I know playing at home is a big advantage with our fans. I don’t know. We’ve got nine more games on this trip. We’ll figure it out.’’

It may be easier, in the short run, if the Red Sox can find a way to get Frank Thomas out. Thomas had three hits – including a homer – and two RBI last night. Including a series while he was with the Toronto Blue Jays earlier this season, Thomas is 7 for 16 against the Red Sox this year with three homers and 10 RBI in just four games.

``He’s had some production against us [this season],’’ acknowledged Terry Francona. ``That’s putting it lightly.’’

Thomas’ first-inning, two-run shot off Tim Wakefield was his seventh homer off the knuckleballer in 51 career at-bats. He later added two singles.

Wakefield managed to limp into the sixth and save some of the bullpen, but was ineffective from the beginning. After giving up three runs in the first – two on the shot by Thomas – he was banged for four more runs in the third, three of which scored on a homer by Mark Ellis.

Kevin Cash, Wakefield’s designated catcher, sensed it might be a long night from the first inning.

``When he really has [the knuckler] going,’’ said Cash, ``you see kind of a late reaction from me. It has that good late movement to it. But tonight, he left some up.’’

``I battled as hard and as long as I could,’’ said Wakefield, who is winless in his last three starts and has only one victory in his last six outings. ``My mechanics are a little off right now. I wasn’t as consistent as I would have liked.’’

Opposing hitters have belted five homers off Wakefield in his last three starts. In two of those three starts, he’s fallen behind by big margins early, trailing 7-0 by the third inning.

Put in a deep hole, the Sox were battling uphill against Oakland starter Rich Harden. Thanks to a shoulder injury, Harden was making only his sixth start of the season last night, but three of them have come against the Red Sox, including two in the first three games of the season.

In those three games, Harden is 2-0 with a 1.59 E.R.A. In 17 innings, he’s allowed 11 hits while striking out 23, including eight last night in six innings.

Labeling Harden’s stuff as on par with anyone in the American League and noting the bad timing the Sox have endured, Francona cracked: ``I hope they’re not going to pitch him Sunday [in the series finale].’’

Harden retired the first 10 hitters he faced before Pedroia nicked him with a one-out, solo shot to left in the fourth.

A leadoff double from J.D. Drew in the fifth and a two-out single from Jacoby Ellsbury in the fifth accounted for the second run, the only other run Harden yielded.

``He had a good fastball, a good slider and he located well,’’ said Drew. ``He kept us off-balance.’’

The Sox used two singles and an infield throwing error for the their final run, off the Oakland bullpen, in the seventh.