"That was fun when I heard that," Pena said of reaching the milestone. "I was like 'What? Two hundred home runs in the major leagues?' It would take me a few minutes to count to 200. That's all I know. That's not one, two, three, four, five. It'll take me a couple of minutes to get there. I'm very happy, I'm very grateful to have the opportunity to be able to actually do anything like that.
"Maybe it's not 500 but to me it's 500," Pena added. "Maybe to the rest of the world it's not 500 but to me, it feels just like it."
The AL home run leader, Pena went 2-for-5 with four RBIs in his fourth multihomer game of the season. He has more home runs (37) than singles (35).
Pena has hit six homers in five games and 11 in 17. He's batting .455 (10-for-22) over his current seven-game hitting streak.
"He looks like he's going to hit the ball hard every time he swings the bat right now," Rays manager Joe Maddon said.
The Rays, who remained three games behind Boston for the AL wild card, have won eight of 10.
Shields (8-10), who had lost four of five starts, allowed three runs and eight hits. He walked two and struck out five.
"I didn't have my good stuff tonight," Shields said. "I don't know what it was. I just didn't feel right out there. I battled through it. It's one of those days where you don't really have anything but, with the team giving me some runs early, it kind of gave me the confidence just to throw strikes and get hitters our early."
Pena put the Rays in front in the second with a two-run drive into the second deck in right off rookie left-hander Brett Cecil (5-3).
The Rays added four more off Cecil in the third. Pat Burrell hit a two-run single and, after a visit to the mound by Blue Jays manager Cito Gaston, Pena hit a second smash even deeper into the second deck in right.
"He's seeing the ball amazing," Shields said of Pena. "Those two balls he hit were no-doubters. I'm really happy for him right now."
Cecil lost his second straight start, the first time this season he has dropped consecutive outings. He allowed six runs, five earned, and six hits in 3 1/3 innings, walked three and struck out three.
"Up in the strike zone, he stayed up most of the time," Gaston said of Cecil. "When he's down he pitches pretty good, his fastball sinks and runs a little bit and his changeup is good down. It looks like he's getting his body out in front of his arm and he's dragging his arm through."
Snider cut it to 7-3 with a homer off the center field restaurant on Shields' first pitch of the seventh, his second homer in three games.
Snider also had the defensive highlight, crashing into the right field wall after making a running catch of Gabe Kapler's liner in the second.
Rays outfielder Carl Crawford (sore lower back) was held out of the lineup and is unlikely to play Wednesday, Maddon said. Crawford left Monday's game after three innings. The Rays are off Thursday and open a four-game series at Detroit on Friday. ... Tampa Bay is 23-23 when facing left-handed starters. ... Rays Double-A left-hander Darin Downs, who suffered a fractured skull when he was hit by a line drive Aug. 17, remains in the hospital but is improving, a team spokesman said. Downs' status will be reevaluated Wednesday. ... Blue Jays pitchers have allowed 10 or more hits in nine of the past 10 games. ... Toronto is 16-34 against AL East opponents.