Hafner doubled home a run and helped get Cleveland's sluggish offense in gear for a 5-1 win over the Pittsburgh Pirates on Friday night.
"It proves that even a rehabbing Hafner can help our lineup," Acta said after the designated hitter was activated from the disabled list and delivered his key hit in a three-run eighth inning.
Cleveland went 10-18 while Hafner was sidelined with a strained right oblique muscle. Since May 23, the Indians were only 6-16, shut out six times and won twice by 1-0. Cleveland moved into a virtual tie for first in the AL Central after the Detroit Tigers lost to the Colorado Rockies.
"I just tried to be a presence in the middle of the order," Hafner said. "It was a fun night."
Manager Manny Acta argued for a three-run homer and the umpires used TV replay, which showed the ball hitting the yellow line atop the right-field wall. It must go over the line to be a homer.
Asked if he thought the ball was gone, Hafner joked: "No. I thought it would hit the yellow line."
Carlos Santana had three hits including a home run for Cleveland, which opened a six-game interleague homestand. He broke a 2-for-26 slump by hitting his eighth homer, a solo shot off Kevin Correia (8-6) that made it 2-0 in the fourth. He also had a bases-loaded RBI single in the eighth.
Josh Tomlin (8-4) bounced back from three consecutive rocky starts. He gave up six hits but no walks over 6 2/3 innings, striking out five.
"I located pitches better tonight," Tomlin said.
"He threw 20 of 25 first-pitch strikes," he said. "That's how he gets people out."
Pirates manager Clint Hurdle also was impressed after Pittsburgh had a four-game winning streak snapped and failed to move three games over .500 for the first time since being 40-37 on July 1, 1999.
"He was very, very efficient," Hurdle said. "He had a real sharp breaking ball to right-handed hitters."
Vinnie Pestano struck out Michael McKenry with two on to end the seventh and then worked a perfect eighth. Tony Sipp pitched the ninth, allowing a walk before getting Garrett Jones to bounce into a game-ending double play.
Cleveland first baseman Matt LaPorta was hurt in the third inning.
"He has a right ankle sprain, but X-rays were negative," Acta said. "That means no fracture. He'll have an MRI exam tomorrow and we'll see then (about possible ligament damage)."
Cleveland scored an unearned run in an odd third inning despite LaPorta's baserunning gaffe. He was hurt when caught in a rundown between second and third base and helped off the field by third-base coach Steve Smith and assistant trainer Rick Jameyson.
LaPorta reached when Pirates shortstop Ronny Cedeno leaped to catch his line drive, but the ball bounced off his glove to second baseman Neil Walker, whose low throw skipped past first baseman Lyle Overbay for an error.
Orlando Cabrera followed with an easy grounder to Cedeno and LaPorta tried to go to third.
"Obviously it's a dumb thing to do," Correia said. "It's not something that's going to happen very often, but we just happened to be changing signs and me going from the windup, which I never do with someone at second, just combined into an odd play that got a run in."
In the Pirates' sixth, Cedeno hit a leadoff double and scored on a one-out single by Xavier Paul, who was out trying for second.
Correia dropped to 7-2 on the road, allowing one earned run and four hits over 5 2/3 innings. Chris Resop bailed him out of further damage by coming on with the bases loaded in the sixth and getting Adam Everett to ground into a force out.
Pittsburgh leads the series 15-13. It was the first time the teams met with both above .500. ... The Pirates' first appearance in Cleveland since 2006 drew 36,549 fans. ... Correia has allowed two earned runs or fewer in eight of nine road outings ... Outfielder Travis Buck was optioned to Triple-A Columbus to clear roster space for Hafner, who hit .345 with 22 RBIs in 32 games before being hurt. ... Valerie Bertinelli, star of the TV show "Hot In Cleveland," delivered the ceremonial first pitch in a unique way to Indians first base coach Sandy Alomar Jr. Wearing an Indians jersey, she took a big windup but then ran the ball to home plate and placed it into Alomar's glove. ... Cleveland signed six more draft picks, including its third-round choice, right-hander Jake Sisco. ... The Indians are 4-0 in interleague games this season. They swept three games against the Cincinnati Reds in May.