Boston Red Sox closer Kenley Jansen made history on Wednesday night, and it came at the expense of his former team, the Atlanta Braves.

The Boston Red Sox have been on a roll since the start of May, going 6-2 entering May 10. They had gone on a two-game skid, including one loss at the start of their series against the Atlanta Braves, the first-place team in the NL East. But, the Red Sox have gotten back in the win column, thanks in part to closer Kenley Jansen making history against his former team.

In the ninth inning, Jansen got Braves catcher Sean Murphy to fly out but then surrendered a double to outfielder Eddie Rosario. Despite the big hit, Jansen wasn't rattled, as he forced second baseman Ozzie Albies to fly out, before getting Travis d'Arnaud to strike out swinging to secure the 5-2 win for Boston.

Kenley Jansen records 400th career save against former team

With that, Jansen recorded his 400th career save, becoming just the seventh pitcher to do so. In fact, he is the second-youngest to reach this milestone at 35 years and 222 days. Francisco Rodriguez was the youngest relief pitcher to accumulate 400 saves, who did so at 34 years and 138 days old.

Furthermore, Jansen threw three pitches at 98.7, 98.5 and 98.4 mph on Wednesday, which are the fastest he's thrown since Aug. 27, 2016, per MLB.com's Sarah Langs.

Jansen spent the majority of his career with the Los Angeles Dodgers, making his debut back in 2010. He then elevated into the team's closer and etched his name as one of the best in the game. In his 12 years, Jansen recorded 350 saves, made it to the All-Star Game three times, and won the World Series in 2020.

After the 2021 season, Jansen hit free agency and signed with the Atlanta Braves, who had just defeated the Dodgers in the NLCS and beat the Houston Astros in six games to win the World Series. In 2022, Jansen pitched in 65 games, where he recorded 41 saves and finished 54 games, both of which led the National League.

Jansen signed a two-year, $32 million contract with the Red Sox this offseason. After this game on Wednesday, Jansen has a 0.77 ERA, a 1.11 WHIP, 85 strikeouts, 22 walks, and nine saves to his credit in 12 games.

On May 10, 2023, Jansen became the seventh closer to record 400 saves in their career.