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Funny how the Detroit Tigers thought they were putting too much pressure on themselves during their struggles down the stretch, then in their AL championship series opener they were so incredibly loose.

Carlos Guillen hugged old friends on the opposing side before the game and manager Jim Leyland did his share of socializing, too.

The way things are going, the Tigers might have many more enjoyable October days ahead.

Brandon Inge hit a solo home run and RBI double from the bottom of the order, Ivan Rodriguez also homered and Nate Robertson pitched the Tigers past the Oakland Athletics 5-1 Tuesday night in Game 1 of the ALCS.

"This is postseason. It's a new slate," Inge said. "It's wiped clean and we can go out there now and forget about everything that happened in the season and have some fun and play some good hard baseball."

And fundamentally sound baseball.

The Tigers battered Barry Zito, turned four double plays and once again relied on their flame-throwing relievers. Only one thing went wrong: Sean Casey, Detroit's No. 3 hitter, left early because of an injured left calf and expected to be out a couple of days.

Game 2 in the best-of-seven series — a rematch of the 1972 ALCS — is Wednesday night, with Oakland's Esteban Loaiza facing Justin Verlander.

Fresh off surprising the New York Yankees in four games in the opening round, the typically free-swinging Tigers worked the count against Zito.

"We thought if we slowed down against him a little bit, it would work a little better," Inge said. "It's huge, get a little momentum going."

The A's ace retired the first eight batters of the game before running into trouble, with 10 of the last 13 Tigers facing him reaching base on the way to a 5-0 lead.

"After that I started to nit pick a little bit instead of coming right after them," Zito said. "This is the playoffs. If you don't get ahead in the count it becomes more exposed than in the regular season."

The wild-card Tigers showed off their gloves, too, tying a league championship series record for double plays, last accomplished by the San Francisco Giants exactly 19 years earlier — on Oct. 10, 1987.

Robertson, who lost Game 1 against the Yankees in his postseason debut, pitched five shutout innings to win for the first time in the Coliseum. The 29-year-old lefty struck out the side to escape a fourth-inning jam after Frank Thomas drew a leadoff walk and Jay Payton doubled him to third.

"That's Nate," said Rodriguez, one of two Tigers players with a World Series ring. "He never gives up. He never feels any weakness up there."

The Tigers are again feeling good about themselves after losing their final five games of the regular-season, starting with Robertson's Sept. 27 outing. And they have all but forgotten that awful 119-loss season from three years ago.

Oakland never trailed in its division-series sweep of the Minnesota Twins, taking quick leads in all three games. This time, the A's grounded into double plays to end both the second and third innings to squander early scoring chances, then had another double play in the fifth.

"We were dodging bullets all night. We just put too many guys on base," Leyland said.

The A's made mistakes resembling some of their blunders in four straight first-round losses from 2000-03 — not the clean, crisp defense they showed in the division series. They also went 0-for-13 with runners in scoring position.

"With three days off, I think guys came in here a little overanxious and tried to do things we don't normally do," Thomas said.

Zito, Oakland's lone All-Star this season, didn't allow a hit until Inge — the No. 9 hitter — lofted a drive that stayed just inside the left-field foul pole with two outs in the third.

Curtis Granderson followed with a double, then Placido Polanco walked on Zito's 56th pitch. After Casey followed with a walk, pitching coach Curt Young paid a visit to the mound before Magglio Ordonez's infield single that five-time Gold Glover Eric Chavez bobbled at third base.

Zito threw 38 pitches, 18 balls, in the inning after needing only 31 to get through the first two, and he gave way to Chad Gaudin after only 3 2-3 innings. His line: seven hits, five runs, three walks and no strikeouts on 92 pitches.

Casey was in a walking boot after the game and Guillen will likely shift from shortstop to fill in at first.

"Hopefully tomorrow it feels a lot better and I'll get treatment and be back in there soon," Casey said. "It's frustrating. I've been down this road before. I'm sure those guys will be fine."

Robertson and his relievers were in control, with Oakland's only run coming on Payton's RBI groundout in the eighth.

Fernando Rodney and Joel Zumaya each reached triple digits on the radar gun, with Zumaya topping out at 102 mph. Todd Jones finished it.

The Tigers — whose deep and talented pitching staff was baseball's best this season — held Frank Thomas 0-for-3 with a walk after the Big Hurt had a hit in each of the A's first three playoff games, including two home runs in the division series opener.

"If they shut us down, you can't be surprised," Chavez said. "They shut down the Yankees."