The struggling slugger homered for the fourth time in eight games Friday night, helping the AL East leaders beat the Detroit Tigers 5-2 and retain a three-game lead in the division over Boston.
"I really believe in our guys," Rays manager Joe Maddon said. "I believe they're going to come through in the clutch and keep getting better."
He was last season's AL Comeback Player of the Year when he hit .282 with 46 homers and 121 RBIs, but hasn't been nearly as consistent this season.
"We don't ever try to project anything into the future. ... We basically show up each day and play the game and just have faith that everything's going to be great at the end," Pena said.
Evan Longoria also hit a solo homer, and Tampa Bay's bullpen limited Detroit to one hit over the last 4 1-3 innings.
Grant Balfour (3-1) struck out three of the four batters he faced in relief of All-Star Scott Kazmir to get the victory. The right-hander, who began the season in the minors, lowered his ERA to 1.20 with just four runs allowed and 45 strikeouts in 30 innings.
Pena's homer off Zach Miner (5-4), snapping a 2-2 tie in the sixth, briefly lifted him into a tie with Longoria for the team lead with 19.
Longoria, leading all major league rookies in home runs, hit No. 20 off Joel Zumaya to make it 5-2 in the seventh.
Dan Wheeler escaped a bases-loaded jam in the seventh after J.P. Howell gave up a double to Curtis Granderson, hit Magglio Ordonez with a pitch and walked Miguel Cabrera, bringing Gary Sheffield to the plate.
Sheffield, who drew a bases-loaded walk from Kazmir in the first, grounded to shortstop to end the threat.
"It's a great feeling," said Balfour, who's allowed no runs and one hit in his last eight appearances. "All the guys are doing our part, one after the next."
Troy Percival worked the ninth to finish the four-hitter, moving ahead of Randy Myers for sole possession of eighth place on the career saves list with 348. The 40-year-old closer has converted 24 of 26 opportunities this season.
The effort by the bullpen made up for a subpar performance by Kazmir, who fell behind 2-0 when he walked four of the first six batters of the game and then gave up a RBI triple to Cabrera in the third.
Although the left-hander only allowed two runs and three hits, he tied a career high with six walks in 4 2/3 innings.
"I thought we did a good job of laying off pitches, getting him in trouble. But we didn't do a very good job of keeping him in trouble," Tigers manager Jim Leyland said. "We let some early chances get away."
Since winning a club-record six straight decisions from May 10 to June 6, Kazmir has only won twice in 10 starts. He's lasted fewer than six innings in seven of those starts, exiting early more often than not because of high pitch counts.
He threw 110 pitches Friday night, departing after giving up a two-out single to Ordonez and issuing a walk to Cabrera. Balfour replaced him and struck out Sheffield to end the inning.
Miner, making his fourth start of the season after 32 appearances out of the bullpen, allowed four runs and eight hits in 5 1/3 innings. His chances of extending his personal winning streak to five consecutive decisions spread over two months was hindered by Detroit's lack of timely hitting.
The Tigers left the bases loaded twice, stranded 12 runners overall and finished 0-for-9 with men in scoring position.
"We just couldn't get a big hit," Leyland said. "It's that simple."
Tampa Bay tied it with two runs in the third. Akinori Iwamura hit an RBI double and eventually came around to score when Brandon Inge, who became Detroit's regular catcher when Ivan Rodriguez was traded to the New York Yankees, failed to handle a low pitch and was charged with a passed ball.
After going 7-for-55 during a 13-game stretch, Crawford has five triples and is 9-for-23 during a six-game hitting streak. ... An MRI revealed Tigers RHP Todd Jones has tenditinitis in his pitching shoulder. The 40-year-old was placed on the 15-day disabled list on Thursday. He expects to get a cortisone shot and hold off on throwing for at least a week. ... Rays OF Rocco Baldelli (mitochondrial disorder) finished a 20-day rehab assignment at Double-A Montgomery. His status will be re-evaluated when he returns to St. Petersburg this weekend. ... Granderson's seventh-inning double extended his hitting streak to 11 games.