DETROIT -- It is a season that so far has exceeded Rick Porcello's expectations -- and a lot of other folks, too.

Porcello improved to 11-4 Tuesday night with his second straight shutout, a four-hitter that increased his string of scoreless innings to 25 1/3, with hot-hitting J.D. Martinez giving him some breathing room with a two-run home run that helped the Detroit Tigers top the Oakland Athletics, 3-0.

The right-hander needed just 95 pitches for his third career complete game. He didn't walk a batter nor did he strike one out in his shutout, the first time that has happened in the majors since lefty Jeff Ballard of Baltimore on Aug. 21, 1989.

"He's attacking the strike zone instead of pitching around it," Oakland manager Bob Melvin said. "His sinker and his changeup are very good and he's got a nice spread (in mph) between them."

Porcello is the first Detroit pitcher with consecutive shutouts since right-hander Jack Morris in 1986 and the fourth Tigers pitcher to turn in a shutout without a walk or a strikeout.

Porcello had a three-hit shutout at Texas in his previous start and threw six shutout innings in a start at Cleveland before that. He began his scoreless innings streak in a June 15 start against Minnesota.

"He's been our most consistent pitcher this season," said right fielder Torii Hunter, who drove in Detroit's first run with a groundout to short in the fourth inning. "And he hasn't even touched the ceiling yet. Not even close."

The 26-year-old has increasingly relied on his changeup and curveball to complement his sinker.

"I gave up so many hits my first five years I've figured out where not to throw the ball," Porcello said. "I'm comfortable that I'm able to make pitch by pitch adjustments now and I'm confident that I can get certain hitters out."

J.D. Martinez, subbing for injured designated hitter Victor Martinez a second straight night, has been equally hot for Detroit.

He got ahold of a first-pitch changeup from lefty Brad Mills (1-1) and put it into the left field seats one out after second baseman Ian Kinsler led off the sixth with a single. It was Martinez's 10th home run of the season.

Mills struck out six, walked three and gave up six hits in six innings for the A's.

"To give up just three runs to a team like that is pretty good," Melvin said. "One on a ground ball and a two-run home run. He gave up three and didn't get anything.

"It was a pretty well pitched game by him. We just didn't get him anything."

J.D. Martinez, who Detroit manager Brad Ausmus had been hoping to give a day off the past two games, is hitting .355 in his last 31 games with all 10 of his home runs and 28 RBI. He has six home runs in his last 15 games.

Detroit scored in the fourth with the help of some aggressive base-running by Miguel Cabrera. The Tigers first baseman, who walked with one out, never hesitated going to third on a double to left by J.D. Martinez. Cabrera scored on Hunter's groundout to short.

The Tigers have gone 9-2 since falling 1 1/5 games out of first place to reclaim the top spot in the AL Central Division.

NOTES: Oakland C Derek Norris (sore back) could start Wednesday's day game. ... DH Victor Martinez was held out of Detroit's starting lineup Tuesday for a second consecutive game. He has a sore back, near the rib cage. ... Oakland LF Yoenis Cespedes, who came out of Monday night's game after eight innings, didn't start Tuesday due to a hamstring strain. "If he plays Wednesday, he'll DH," manager Bob Melvin said. ... Tigers CF Austin Jackson was moved back to the leadoff spot in an effort to end his two-month slump but was 0-for-4 Tuesday. ... A's LHP Scott Kazmir reported to the park feeling good Tuesday after sustaining a calf cramp that limited him to 5 1/3 innings in his Monday start. Kazmir will throw his regular bullpen session and then make his next start as scheduled, Melvin said.