It's hard to keep Kotsay's bat in check

ST. PETERSBURG, Fla. - He's an accidental hero, particularly after an accidental swing.

Mark Kotsay wasn't supposed to be a starter when the Red Sox acquired him from Atlanta Aug. 27. Listed as an outfielder on the Red Sox' postseason roster, he's not supposed to be playing first base. And Kotsay wasn't supposed to swing at a first-pitch fastball during the fifth inning last night.

But all of that happened. Thrust into the lineup at first base because of the hip injury that sidelined Mike Lowell (forcing Kevin Youkilis to shift to third base), Kotsay produced arguably the game's biggest hit last night with a checked-swing double that helped the Sox top the Rays, 2-0, in Game 1 of the American League Championship Series.

Batting with no outs and Jason Bay on first in a scoreless game, Kotsay couldn't hold his swing at a fastball from James Shields. The 89-mile-per-hour heater was sprayed off the excuse-me swing and landed gently along the line in left field, and Kotsay legged out a double to put runners on second and third.

Rookie Jed Lowrie followed by lifting an 0-and-2 changeup to right, allowing Bay to tag and score the game's first run. Kotsay also advanced, but was stranded at third.

"I got lucky," said Kotsay. "I took a checked swing and the ball ended up finding some outfield grass and turned into a double. That's part of the game.

"You can square a ball up, have a good cut, run back to the dugout, and feel sorry for yourself. Then you take a checked swing and get a double that eventually led to a run."

Kotsay nearly repeated the feat in the seventh. Batting with no outs and runners on first and second, he once again connected with a checked swing (this time a 1-and-0 changeup from Shields) and the ball floated dangerously toward shallow center field before Rays second baseman Akinori Iwamura ran it down.

"I don't take too many checked swings," said Kotsay. "For some reason, the next at-bat I checked [my] swing again. I don't know, it's just one of those funny, goofy things. Fortunately, one out of the two got a hit."

Like the hit, the fact that Kotsay is in the starting lineup is goofy enough.

A veteran of 1,450 major league games and Oakland's postseason run in 2006, he was brought to the Red Sox as outfield insurance with J.D. Drew nursing a back injury late in the season. Kotsay was supposed to add depth to an already crowded outfield that featured Drew, Bay, Coco Crisp, and Jacoby Ellsbury.

What's more, the Red Sox already had Sean Casey as a backup first baseman. But Kotsay - he of just 16 starts at first base before coming to Boston - proved too good of an all-around player to keep on the bench.

He appeared in three of the Sox' four games in the Division Series, staring Games 2 and 4 at first base and going 3 for 9 in those starts.

Acquired from Atlanta in exchange for minor league outfielder Luis Sumoza (this after the Sox' initial post-trade deadline move to land Brian Giles was blocked by the San Diego outfielder), Kotsay started 18 regular-season games in right field and four at first base for the Sox.

"I came here with a lot of confidence," said Kotsay. "When I got here, they had injuries to J.D. and a couple other guys in here. I didn't know my role, but I knew that I would get slotted in here somewhere and hopefully I would contribute."

And like his teammates, he's learned to take advantage of every situation.

"We're relentless," said second baseman Dustin Pedroia. "We're going to find a way to beat the other team . . . Kotsay has been great."

Game 1 wasn't all it could have been for Kotsay. He came up with the bases loaded and two outs in the eighth, but popped to third base with a chance to deliver a knockout blow.

Maybe he should have half-swung at the ball.

Chris Forsberg can be reached at cforsberg@boston.com.