Last month's All-Star break came at just the right time for Arizona Diamondbacks starting pitcher Zac Gallen, who has returned to form since the season's second half began.

Arizona has lost four straight and could use another strong outing from Gallen when he takes the mound against the host Cleveland Guardians on Tuesday.

Gallen (5-2, 3.24 ERA) is 1-0 with a 0.75 ERA in two starts since the All-Star break. The right-hander yielded two runs (one earned) on three hits over five innings against the San Francisco Giants on Wednesday.

"I just had a chance to reset over the break," Gallen said. "Sometimes the break will be good or bad. In this case so far, it's been pretty good."

Gallen will be making his first career appearance against Cleveland, which opened the three-game series with a 6-5, 11-inning victory on Monday.

The Guardians' Andres Gimenez established career highs with four hits and three stolen bases in the Monday victory. Amed Rosario added three hits and three RBIs, including a two-out single that scored the winning run in the 11th inning.

Cleveland rookie left fielder Steven Kwan had two hits on Monday and is batting .362 (25-for-69) with 14 runs and five RBIs during his career-high, 15-game hitting streak.

"He's beyond his years," Guardians manager Terry Francona said of the 24-year-old. "He's learning so fast. ... He's a keeper."

Cleveland, which has won 10 of its past 15 games, will send right-hander Triston McKenzie (7-7, 3.24 ERA) to the mound on Tuesday. He is hoping to pick up where he left off in July, when he went 3-1 with a 1.34 ERA in five starts.

McKenzie, 24, cruised through five innings against the Boston Red Sox on Thursday before allowing a three-run homer in the sixth to Xander Bogaerts.

"I thought he was so good," Francona said. "I mean, really good. Then they had the 0-2 swinging bunt, and then he made a couple of bad mistakes. And then the last one, the 0-2 breaking ball for the three-run homer, that really hurt. But up to that point, man, he was so good."

McKenzie allowed four runs on six hits over seven frames, with one walk and six strikeouts, in the 4-2 loss to the Red Sox. He will be making his first career appearance against Arizona.

The Diamondbacks made a move ahead of Tuesday's trade deadline, sending right-hander Luke Weaver to the Kansas City Royals in exchange for infielder Emmanuel Rivera.

Weaver, 28, was acquired from the St. Louis Cardinals as part of the Paul Goldschmidt trade in December 2018. He posted a 7.71 ERA in 12 appearances (one start) this season.

Rivera, 26, has hit .243 with seven homers in 288 career at-bats over the past two seasons. He played third base and first base for the Royals this season.

"Rivera is a guy we've liked for a while, just his ability to hit left-handed pitching and play third base," Arizona general manager Mike Hazen said.

The Diamondbacks will be without left-handed reliever Caleb Smith for an extended period after he was placed on the 15-day injured list with a fractured right hand.

Smith, 31, sustained the injury while throwing a punch in anger after giving up two runs in two innings against the Atlanta Braves on Saturday.