PHOENIX (AP) -- Mat Latos started a new winning streak in grand style.
The Cincinnati right-hander went 21 starts without a loss before Pittsburgh beat him on Tuesday. His next time out, he matched his career high with 13 strikeouts Sunday in a 4-2 victory over the Arizona Diamondbacks.
''When he's good, he's real good,'' Reds manager Dusty Baker said.
Shin-Soo Choo hit a leadoff home run and Brandon Phillips added a two-run shot in the first inning off Randall Delgado (0-1) as the Reds averted a three-game sweep.
That was plenty of offense for Latos (7-1), who allowed a run on six hits with one walk in 7 2-3 innings.
''The first inning it took me a little while to I guess get into a groove,'' he said. ''The first inning I didn't feel too good, didn't feel too great with my command. Then I came out in the second inning and made a little bit of an adjustment, and it worked.''
Latos didn't strike anyone out in the first two innings, then fanned 13 over the next 5 2-3.
''Not too many guys score against this guy,'' Arizona manager Kirk Gibson said. ''Look what he has done over the last 20 starts. We hung in there. We gave ourselves a chance to win. We hung in there enough to get him out of the game. You are not going to win them all.''
After blowing a save in Cincinnati's 4-3 loss on Saturday, Aroldis Chapman gave up a run in a shaky ninth but still got his 19th save.
The loss snapped Arizona's four-game winning streak.
In the ninth, Chapman got the first two batters to bounce out to shortstop before Cliff Pennington singled and went to second on defensive indifference. Pinch-hitter Wil Nieves singled in Pennington to cut it to 4-2.
A wild pitch moved Nieves to second, then Chapman hit Gerardo Parra in the right forearm with a 100 mph fastball.
Pitching coach Bryan Price went to the mound to settle down Chapman, and the left-hander got Willie Bloomquist to pop out to center to end the game.
Latos fanned six in a row in the third and fourth - Delgado, Parra, Bloomquist, Paul Goldschmidt, Miguel Montero and Jason Kubel - all swinging. Of Latos' season-high 110 pitches, 79 were strikes.
''Can't complain with that,'' Latos said.
The big strikeout number was a mixed blessing, he said.
''You start striking out a lot of players, you start throwing a lot of pitches,'' Latos said. ''Maybe it would have been great to go all nine and not strike out 13, but I'll take it. It was a good win.''
He said his slider ''felt good coming out of my hand.''
''That and the changeup,'' he said. ''The changeup is a pitch I've been working on all season.''
The Reds jumped on Delgado from the start.
Choo hit an 0-2 pitch into the swimming pool area in right field, his fourth leadoff homer of the season and ninth of his career. Zach Cozart followed with a double, then after Joey Votto struck out looking, Phillips' homer to left made it 3-0.
Choo and Phillips each have 11 home runs this season.
Phillips had been hitting .164 since missing four games after he was hit by a pitch in the left forearm at Pittsburgh on June 1.
''It felt good to come through for the team,'' he said. ''I haven't been doing my job lately but you know I'm trying, I'm trying to step my game up. I'm not my normal self. I'm not 100 percent, but the thing is there's no excuses. I'm still in the lineup so I've got to do my job.''
Cincinnati added an unearned run in the second. Xavier Paul led off with a double, then Pennington bobbled Devin Mesoraco's grounder down the third base line for an error. Latos sacrificed the runners to second and third, and after Choo walked to load the bases, Cozart brought Paul home with a sacrifice fly to the wall in left-center.
Delgado went five innings, allowing four runs - three earned - and six hits.
The right-hander, who came to Arizona from Atlanta as part of the Justin Upton trade, made his second start since being called up from Triple-A Reno to bolster a rotation depleted by the 10-game suspension of Ian Kennedy and a shoulder injury to Brandon McCarthy.
The Diamondbacks broke through in the eighth when Parra doubled with one out, then advanced to third on Bloomquist's groundout. Goldschmidt drew a two-out walk and Montero singled Parra home to make it 4-1, maintaining Arizona's status as the only team in the majors not to be shut out this season.
Left-hander Manny Parra relieved Latos and got Jason Kubel to ground out to first to end the inning.
NOTES: After the game, Gibson said 2B Aaron Hill, on the DL since April 14 with a broken left hand, would be activated Tuesday. LHP Joe Paterson was optioned to Triple-A Reno to make room. ... Arizona starters do not have a win in their last 16 games. ... Latos struck out at least 10 for the second time this season and seventh in his career. ... The Reds played for the 17th day in a row. They have a day off Monday, then open a two-game series in Oakland with Bronson Arroyo (6-5, 3.13 ERA) on the mound for Cincinnati and Tommy Milone (6-7, 3.98) going for the A's. ... Arizona has Monday off, then opens a three-game series at Washington on Tuesday. Trevor Cahill (3-8, 3.92) pitches for the Diamondbacks against Gio Gonzalez (3-3, 3.34). ... Pennington started at 3B for the first time since 2008.