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Seeking his fourth win in five starts, Blue Jays' Shaun Marcum will face a Diamondbacks offence that has scored at least eight runs in each of its last four home games, all wins. ((Elsa/Getty Images) )

After struggling with consistency, the Arizona Diamondbacks offence has found its groove during a season-high, four-game win streak.

A matchup against red-hot Toronto Blue Jays starter Shaun Marcum, however, might cool off the Diamondbacks' bats.

Marcum will try to earn his fourth win in five starts and third in as many outings as he faces the Diamondbacks for the first time in Sunday's finale of a three-game road series for the Jays at 4:10 p.m. ET.

Before its current win streak, Arizona (20-24) batted .220 and was outscored 88-46 in losing 10 of 14. That seemed to change with a 13-1 victory over San Francisco on Wednesday.

Beginning with that rout, the Diamondbacks — 0-6 on their previous homestand — have scored at least eight runs in each of their four straight home wins while batting .326. First baseman Adam LaRoche has led the way by hitting .533 (8-for-15) over that stretch with three homers and eight runs batted in.

Chris Young has been right behind LaRoche, batting .500 and drove in four runs in Saturday night's 8-5 victory over the Blue Jays. In a familiar theme in this season, the Diamondbacks scored all of their runs in the first two innings.

They got six of their eight runs in the first four innings of Friday's 8-6 win.

"We're jumping on top early on teams and putting good at-bats together," third baseman Mark Reynolds said. "We went through a little slump there for about a week and couldn't string anything together. Now we're stringing stuff together."

Billy Buckner (0-1, 3.60 earned-run average) will try to benefit from that support in his second start of the season. The right-hander gave up just two runs over five innings Tuesday in Florida but was on the wrong end of an 8-0 defeat.

Poor run support

Until an 11-2 win over Minnesota that same day, Marcum (3-1, 2.61) also hadn't received the benefit of generous run support (3.93 runs per outing) this season. The right-hander has overcome those recent inconsistent efforts from his offence with a 1.54 ERA in his last five outings.

He has allowed one run or fewer in four of those starts, including Tuesday's win against the Twins. After giving up one run and five hits in that victory, he flew off to Dayton, Ohio, for his grandmother's funeral.

"Today was really special," manager Cito Gaston told the team's website. "He was kind of pitching with a heavy heart out there. … It wasn't easy out there for him. But, man, he stood up and did a great job for us."

Toronto (25-20) will try to avoid its fourth straight defeat and seventh in 10 road games by extending its win streak in Marcum's recent appearances. The Blue Jays have won four in a row when the right-hander has pitched.

"When Shaun's on the mound, you know what you're going to get," outfielder Vernon Wells told the Blue Jays' official website. "He's going to battle and give you some innings."

The Diamondbacks will try to stop that streak by completing their five-game homestand unbeaten. Arizona is riding its longest win streak at Chase Field since a seven-game run to conclude 2008.

Arizona has never recorded a home sweep in interleague play and hasn't won three in a row against an American League team since beating Baltimore from June 15 to 17, 2007.