OAKLAND -- Jeff Samardzija arrived in Oakland just in time to watch his new team do what they do best -- win.
Scott Kazmir shut down the Blue Jays after a rocky first inning and Josh Donaldson hit his 19th home run of the season as the A's defeated Toronto 5-1 Saturday night for their 54th win of the season -- the best mark in baseball.
The A's are enjoying their longest stretch of consecutive days in sole possession of first place in the AL West since 1990, and their win Saturday puts Samardzija in position to earn his new team a four-game series sweep against the Blue Jays on Sunday.
[RELATED: Samardzija to debut Sunday vs. Blue Jays]
Former Athletic Chris Carter's grand slam wasn't enough for the Astros in LA, so the A's maintain their 3.5-game division lead over the second-place Angels.
Starting pitcher report
Scott Kazmir again showed why he's worthy of the two-year, $22 million contract he received prior to this season, spinning seven masterful innings of three-hit ball.
But it didn't start smooth. It took just five pitches for Kazmir to find a stressful situation. Soft singles from Jose Reyes and Melky Cabrera put men at the corners with the meat of a dangerous order coming up and nobody out. Kazmir stood tall, though, inducing a pop out from Jose Bautista and a double play ball from Edwin Encarnacion.
While Alberto Callaspo made an impressive over-the-back catch on Bautista's fly, his slow transfer on the subsequent ground ball allowed Encarnacion to stretch for first base safely, and Reyes' run to count for a 1-0 Toronto lead.
Encarnacion injured himself on the play, suffering what the Blue Jays officially called "right quad soreness," and Kazmir seemed to steel himself during the delay.
He fanned Dioner Novarro on three pitches to end the long inning and breezed through the next six, allowing just an infield hit to Brad Glenn -- the first of his career -- along the way.
Kazmir now has 10 wins before the All-Star break for the second time in his career. In his last five starts in Oakland, he is 5-0 with a 1.00 ERA.
Kazmir's final line: 7 IP, 3 H, ER, 2 BB, 8 K, 113 P, W.
Luke Gregerson took the mound in the eighth inning and benefited from two impressive defensive plays to escape unscathed despite allowing a single and a double.
Fernando Abad pitched the ninth without incident.
At the plate
The A's collected at least one hit in each of the first six innings and added five runs to their MLB-leading total of 435.
Josh Donaldson took advantage of Brandon Moss' absence from the lineup, crushing a 2-0 offering out to center in the third inning to tie the game and Moss for a share of the team lead in homers with 19.
The A's struck again an inning later with a two-out rally in the fourth when Alberto Callaspo and Stephen Vogt turned the lineup over and Coco Crisp and Craig Gentry delivered RBI singles.
Oakland added two insurance runs in the eighth inning after Nate Freiman and Jed Lowrie led off the inning with a single and a double, respectively.
The A's are now 29-3 when outhomering their opponent, as they did Saturday.
In the field
The A's played clean defense behind Scott Kazmir, saving their best plays for the eighth inning.
Donaldson went hard into the tarp on the left-field line in the eighth, gloving a popup to retire leadoff hitter Munenori Kawasaki and draw "M-V-P" chants from the crowd.
Then, Craig Gentry and Jed Lowrie teamed up for a textbook relay to nail Melky Cabrera at the plate to end the inning. Cabrera reacted as though he was safe, but after a two minute and 30 second replay delay, the call was confirmed.
The A's announced a paid attendance of 20,236. It seemed all offered loud boos before each of Cabrera's plate appearances.
The A's and Blue Jays wrap their four-game series Sunday afternoon and it will be the newcomer Samardzija (2-7, 2.83 ERA with Chicago) making his Oakland debut against Blue Jays right-hander Drew Hutchison (6-6, 3.81). A's Pregame Live gets you ready at 12:30 p.m.