The Mets swept the Cardinals to win a sixth straight series, the first time the season started in franchise history.

ST. LOUIS. Six wins in a row at the start of the year? It will play.

Backed by Chris Bassit on Tuesday, six straight innings, the Mets beat the Cardinals for the second night in a row, this time 3-0, to secure Amazin’s series win ahead of their final at Bush Stadium on Wednesday. For the first time in franchise history, the Mets won their first six series of a season.

“We started off fast, but I’m more excited about the last six episodes of the year than the first six,” Bassitt said. “We have a long way to go. Just keep grinding.”

A good serve will go a long way, and the Mets are reveling in that honor after 13 combined scoreless innings from their starters in the Cardinals’ first two games of the series. After Max Scherzer threw seven shutout innings in the team’s win on Monday, Bassitt followed him with six scoreless innings against the Cardinals hitters. Bassit’s three wins in the season are tied with five other wins, including rotation mates Scherzer and Tylor Megill, for the most National League wins.

“I think the impact that a lot of our players have had on each other is obvious,” said Mets manager Buck Showalter.

Bassitt gave up just two hits and recorded six strikeouts, three walks in 94 pitches. The right-hander has allowed at least one Cardinals batter to reach base in five of his six innings, but has managed to stop those runners every time. Luckily for Bassit, he teed off 12 of his last 14 batters to take the lead and gain the lead.

James McCann enjoyed a 3-for-4 hitting all fields as the Mets catcher looked to be attacking a bit. His first hit of the game, a 388-foot RBI double to the warning lane in center field, put the Mets on the board. His second hit was a single on the right and his third was another single, but this time on the left. McCann also hit his first home run of the season at Chase Field against the Diamondbacks last Friday.

“I feel good, but the process is more important than the results,” McCann said, adding that last week he changed the position of his hands on the bat, which has so far led to a positive result on the plate.

Things escalated at the end of the serve after Pete Alonso was hit by Cody Wheatley’s helmet serve in the eighth round. Whitley’s 83 mph replacement hit Alonso squarely on the C-flap of his helmet, the second time this season a Mets first baseman was hit with a headbutt. Alonso fell to the ground, but immediately got back up, and, visibly heated, the slugger seemed to exchange a few words with Wheatley before running to first base.

Showalter was the first to get out of the dugout, but he headed straight for first base to check on Alonso, who appeared to be fine and stayed in the game. The Mets players came off the bench and spilled onto the field, but remained on the grass behind the third base line, while the Cardinals remained in their dugout. The referees issued a warning to both teams, and when the situation calmed down, composure prevailed.

“It’s one thing to get hit in the toe or knee, but we get a lot of hits in the head and neck,” Showalter said. “It’s just not good. . . You are reaching the point when it comes to the safety of your players. We were lucky. You’re talking about the field where the helmet broke (Alonso). This is not good. Unhappy.”

Alonso was one of three Met hitters eliminated on Tuesday. Dominic Smith and Starling Marte were also hurt by the serve, with Marte coming out in the ninth inning after warnings had already been issued. But the judges decided that there was no intent, so no one was expelled.

However, tensions in the Metz dugout were clearly high as Scherzer was seen yelling at the Cardinals from his position on the top step of the railing. Marte’s hit on the field was the 18th time the Mets have been in practice this season, which is a major league leader. Alonso and Marte are tied for the lead in the big leagues with four fielding hits this season.

“It’s uncomfortable,” said Marte about being coached. “At the end of the day, this is one of those things where, whether intentional or not, it has to stop. We are tired of this. We will have to do something about it if this continues, because every time you go out you get beaten up and it’s embarrassing.”