When Edwin Encarnacion steps to the plate these days, everyone in the Toronto Blue Jays dugout makes sure they've got a good view.

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," Blue Jays 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," Blue Jays 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 American League 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 major leagues with 70 home runs and have connected in eight straight games. Toronto has hit 38 homers in May, best in the majors.

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."

Josh Donaldson hit a leadoff homer off Dustin McGowan in the eighth for Oakland's only run. Casey Janssen finished for his seventh save in as many chances.

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.

Bautista greeted reliever Jim Johnson with a first-pitch RBI single in the fifth, but Jose Reyes was thrown out trying to score from second on a one-hop throw by Yoenis Cespedes.

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 centre field.

After a review of two 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.