Updated

The Oakland Athletics can wrap up their second straight American League West title on Sunday when they try to complete a four-game sweep of the Minnesota Twins at O.co Coliseum.

Oakland lowered its magic number for clinching the division to one on Saturday, as Alberto Callaspo smacked a two-run homer among his three hits and three RBI in the Athletics' 9-1 win.

Yoenis Cespedes cracked a solo shot among his two hits, three RBI and two runs scored for Oakland, which can win the AL West with a victory on Sunday or a Texas Rangers loss.

The A's moved to 15-5 in September.

"We're swinging the bats well and adding on and hitting home runs and doing a lot of things that we continue to do," Oakland manager Bob Melvin said.

Jarrod Parker (12-7) surrendered a run on four hits over six frames in the triumph.

Spurts of heavy rain delayed the start of the contest for just over two hours.

Pedro Hernandez (3-2) allowed six runs on eight hits and a walk in a two- inning start for Minnesota, which has dropped nine of its last 11 tilts.

"Any mistake you make right now they jump on you," Minnesota manager Ron Gardenhire said.

Getting the call for the A's on Sunday will be righty Sonny Gray, who is 3-3 with a 2.50 ERA. Gray did not get a decision on Tuesday against the LA Angels, but pitched well, allowing just a run and five hits in six innings of his team's 2-1 win.

Gray beat Minnesota two starts ago, holding it to a pair of runs in five innings.

Minnesota, meanwhile, will hand the ball to righty Cole De Vries, who will be making his first start of the season. De Vries has appeared in two games out of the bullpen for the Twins and has pitched to a 7.88 ERA without recording a decision.

In 16 starts last season De Vries went 5-5 with a 3.99 ERA.

Oakland took two of three from the Twins last week at Target Field.