CLEVELAND -- The Indians could have used a mop to finish this sweep.
Duncan ripped a pitch from left-hander Matt Thornton (1-2) into the left-field corner, scoring Asdrubal Cabrera as the first-place Indians won for the eighth time in 11 games. After the Indians led the AL Central for nearly five months last season before fading, Duncan believes they are better prepared to finish what they've started.
"I don't feel like we're playing over our shoes," he said. "We're more in control. We're a good team."
The Indians won the opener 8-6 behind Zach McAllister, who came up from Triple-A Columbus, and an offense that pounded Philip Humber into submission. Also, Nick Hagadone got his first major league save in the opener, and Tony Sipp earned the second save of his career in the nightcap, saving manager Manny Acta's bullpen.
"We're playing good baseball," said Acta, whose team got off to a 30-15 start in 2011 before the late-season collapse. "We're playing better baseball at home, and it seems like we're getting the hang of it again."
Meanwhile, the White Sox have lost six of seven and dropped to 2-6 just beyond the halfway point of a 15-game stretch against division opponents.
"It's not fun to go through it," first-year manager Robin Ventura said. "It gets frustrating, but the way guys are grinding, you can't fault them for anything. It's just the way it goes."
Cleveland's Josh Tomlin allowed five hits in 7 1/3 innings -- most of the final three in a steady downpour. He struck out a career-high eight, allowed two walks and maintained his control despite slick, slippery conditions on the mound.
Joe Smith (2-1) gave up a game-tying single after a lengthy rain delay but got two outs and was credited with the win after Duncan's single.
Sipp worked the ninth for his first save, getting Tyler Flowers to ground to second with one on for the final out a few pitches after Chicago's catcher hit a long fly ball that nearly left the ballpark.
"Get ahead [in the count], right?," Smith said, poking fun at Sipp, who got his first save since July 23, 2010. "It doesn't matter if it goes 500 feet as long as it goes foul."
Cleveland's Travis Hafner homered and tripled in the opener. He struck out twice in the second game but was hit by a pitch for the 79th time in his career, tying him with Nap Lajoie for the team record.
Cabrera opened the eighth with a bloop single off Thornton, and Carlos Santana followed with a flair to almost the exact spot in shallow right-center. After Hafner popped out, Duncan pulled Thornton's pitch down the line to make it 3-2 and give the few hundred fans who stuck around after a lengthy rain delay something to cheer.
The White Sox tied it 2-all in the eighth, moments after a 1-hour, 25-minute rain delay, on Alex Rios' RBI single.
With the sky darkening and radar showing heavy rain approaching, the Indians scored twice in the fifth to take a 2-1 lead and put Tomlin in position for the win.
Tomlin retired the White Sox in order in the sixth and seventh before running into trouble in the eighth as the rain intensified. With one out, he walked Alejandro De Aza and gave up a single to Gordon Beckham before Acta decided to pull his right-hander and bring in reliever Dan Wheeler.
But as Wheeler neared the mound, crew chief Larry Vanover ordered the groundscrew to cover the infield at 9:09 p.m. The rain delay lasted 85 minutes, and when play resumed, Acta put in side-armer Smith, who wasn't supposed to pitch, to face Rios, who promptly hit an RBI single to tie it at 2.
The Indians, though, pulled this one out in the late innings, as they did so many times last season.
"I think we have more confidence that a year ago," Smith said. "We had young guys who gained a lot of experience, and we're building off that and hopefully we can keep it going."
In the opener, McAllister allowed two earned runs and six hits in a career-high six innings. He walked one, set a personal best with six strikeouts and planned to celebrate his victory by hanging around before heading back to Columbus.
"Yeah," he said with a smile. "I'll stay for the second game."
Meanwhile, Humber has gone from perfect to perfectly flawed.
Humber (2-1) couldn't get out of the third inning as the Indians tagged him for eight runs and nine hits in 2 1/3 innings. He hasn't been sharp since pitching the 21st perfect game in major league history last month. Since then, Humber has allowed 20 runs in 13 1/3 innings and gone 0-2 with a no-decision.
"I'm frustrated," Humber said. "I'm doing my best; it's just the last two or three times out there, it's been rough. I'm definitely hoping for better results. I'm doing the best I can to make that happen, but right now it's kind of a grind."
Cleveland moved six games over .500 for the first time this year. ... Per the new collective bargaining agreement, teams are allowed to carry 26 players on their roster for unique doubleheaders. ... The day-night twinbill drew just 19,679 total fans. Despite being in first place, the Indians have the lowest average attendance in the majors. ... Tomlin has given up only 47 walks in 273 career innings. ... Hafner's triple in the opener for Cleveland was his first since 2007, prompting a few good-natured jokes about his blazing speed. "I'd say I could beat 75 to 80 percent of the guys on the team in a race, if it came down to it," he quipped. ... LHP Eric Stults made his debut for the White Sox in the second game and allowed two runs in six innings.