CINCINNATI (AP) — Mat Latos didn’t so much mind his long streak ending. A pitch that plunked his teammate left a mark he won’t quickly forget.

Pedro Alvarez singled home a pair of runs in the first inning, and the Pittsburgh Pirates ended Latos’ streak of 21 regular-season starts without a loss, beating the Cincinnati Reds 4-0 on Tuesday night.

Latos (6-1) hadn’t lost a regular-season game since last August, setting a club-record streak of avoiding defeat. He couldn’t overcome Pittsburgh’s three-run first inning set up by his uncharacteristic control problems.

“I was aggravated with myself,” Latos said. “I didn’t throw too well in the bullpen and kind of took it into the first. I beat myself today. It’s always hard when you put your team in a 3-0 hole.”

Latos had nine of Cincinnati’s 17 strikeouts, which matched the club’s nine-inning record. The Reds also had 17 strikeouts on opening day, but that came in a 13-inning loss against the Los Angeles Angels.

The Ohio River rivals have split the first two games of their four-game series, leaving the Reds a half-game ahead of the Pirates. They’ve been right behind the NL Central-leading Cardinals most of the season.

There was an undercurrent from Monday’s game, when Reds closer Aroldis Chapman threw an up-and-in fastball that leveled Neil Walker. The Pirates weren’t happy about the pitch’s location.

Charlie Morton (1-1) hit Shin-Soo Choo on the leg with his first pitch of the game. Morton also threw one inside to Joey Votto, who refused to budge from the box. Votto flied out, and that was the end of the drama.

Latos yelled from the dugout after Choo got hit. Latos hit Walker in the first inning in Pittsburgh last Saturday, prompting plate umpire Bob Davidson to warn both teams.

The Pirates have hit 39 batters, most in the majors.

“It’s time somebody stepped up and did something about the team that’s hit more guys in the league than anybody,” Latos said.

“I got fined for hitting Neil Walker, but you’ve got a team drilling guys over and over again. It’s time for the league to step up and end it. That fired me up.”

The focus shifted back to Latos’ long winning streak.

The right-hander hadn’t lost since Aug. 24, when the Cardinals beat the Reds 8-5. In the last 21 starts, he’d gone 10-0 with a 2.80 ERA. The Reds were 17-4 during that streak. Also, Latos had never lost to the Pirates, going 4-0 in eight starts with a 2.29 ERA.

Finally, they caught him in a slow start.

He struggled with his control at the outset, needing 32 pitches to get through a 19-minute first inning. Starling Marte tripled and scored on Russell Martin’s infield single, giving Pittsburgh a run after only four pitches. Latos walked Garrett Jones and Walker, and Alvarez singled for two more runs.

“He was all over the place,” manager Dusty Baker said. “They had a couple of hustle plays on their end that were big. He was out of sorts, but after that, he settled down. He got his pitch count up, and we had to get him.”

Latos settled down after the first, fanning eight of the next 11 batters. The problem was his pitch count, which was at 88 when he left for a pinch hitter with two runners aboard in the fifth inning. His streak was left in the hands of the bullpen and the offense.

They couldn’t bail him out. Marte singled home another run in the seventh.

Morton was better during his second start since returning from elbow surgery. He gave up three singles and threw 61 pitches in 5 1-3 innings, starting the Pirates toward their NL-leading 12th shutout.

Cincinnati’s lineup managed four hits while getting shut out for the second time in their last four games.

Morton dominated the Reds in 2011, giving up only one run in two complete games at Great American Ball Park. He had his right elbow rebuilt last June 14 and returned to the majors last Thursday, allowing four runs and seven hits in five innings of a 10-0 loss to San Francisco.

He was much better this time, an encouraging sign for a Pirates rotation hit hard by injuries.

NOTES: The Pirates agreed to terms on Tuesday with C Reese McGuire, their first-round pick and the 14th overall selection in this month’s draft. … Pirates LHP Wandy Rodriguez, on the 15-day DL retroactive to June 6 with a tight left forearm, will throw all of his pitches in a bullpen session on Thursday. If he comes out of that without problem, he will make a rehab start in the minors on Sunday. … Choo has been hit a career-high 19 times, most in the majors.

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