Encarnacion hit a towering home run, J.A. Happ won his third straight start and the Blue Jays completed a three-game sweep of Oakland, beating the Athletics 3-1 on Sunday.
Encarnacion hit a one-out drive into the second deck off Oakland left-hander Drew Pomeranz in the fourth. The homer was Encarnacion's 12th this month, tying the team record for May set by Jose Bautista in 2010.
"You've got to make sure you're watching," catcher Erik Kratz said of Encarnacion's at bats. "He makes the game look a little bit easier. It's definitely exciting to watch."
The Blue Jays' record for home runs in a month is 14, set by Bautista in June, 2012. With six games remaining before the calendar changes, Encarnacion is putting that mark in serious peril.
"When he gets hot, nobody can stop him," shortstop Jose Reyes said of Encarnacion.
Encarnacion's 14 home runs this season are tied for third most in the majors. Only Baltimore's Nelson Cruz (16) and Chicago White Sox Jose Abreu (15) have hit more.
The Blue Jays, who lead the AL East, won their season-best sixth straight. It's Toronto's longest streak since an 11-game run last June. The Blue Jays have won 11 of 13 and 16 of 21.
"We caught them when they were hot and they handed it to us," Athletics manager Bob Melvin said.
The Blue Jays lead the majors with 70 home runs, and have connected in eight straight games. Toronto has hit an ML-best 38 homers in May.
The AL West-leading Athletics lost their fourth straight, their longest losing streak of the season. Oakland, which came in leading the AL in runs, has scored just seven times in the past four games.
"You're not always going to score seven, eight runs a game and right now we're going through a drought," Melvin said.
Happ (4-1) allowed four hits in a season-high seven shutout innings. He walked three and struck out a season-high seven.
"He's filling up the strike zone," Blue Jays manager John Gibbons said. "He's locked in right now."
Encarnacion's homer snapped a streak of 18 scoreless innings by Pomeranz, who hadn't allowed a run since the eighth inning of a May 2 loss at Boston.
One batter latter, Gibbons was ejected for the first time this season after losing a replay challenge.
Gibbons challenged after second base umpire Paul Schrieber ruled that Bautista had been forced out on Encarnacion's blooper to shallow center field.
After a review of 2 minutes, 24 seconds, it was ruled that Schrieber's call stood. Gibbons returned to the field to argue and was quickly ejected by home plate umpire Mark Carlson.
Toronto made it 3-0 in the seventh when Reyes singled off Luke Gregerson, stole second and third and scored on Bautista's sacrifice fly.
Pomeranz (4-2) allowed two runs and five hits in four innings, the shortest of his four starts this season. The left-hander walked a season-high four and struck out three.
Reyes matched a career high with three stolen bases, achieving the feat for the first time since September 2008. ... Oakland INF Nick Punto (left calf) missed his second straight game. ... Encarnacion, Bautista, Melky Cabrera and Reyes wore pink armbands to mark Mother's Day in the Dominican Republic. ... Attendance was 45,277, Toronto's fourth sellout of the season. ... Oakland returns home Monday to host Detroit. Tigers LH Tommy Milone (2-3) faces Athletics LH Drew Smyly (2-2). ... Toronto begins a three-game series against Tampa Bay on Monday. Rays LH Erik Bedard (2-2) faces Blue Jays RH Drew Hutchison (3-3).