In pitching a perfect 9th inning in a 6 – 5 win against the Rangers, Craig Kimbrel of the Red Sox becomes the 29th man to record 300 saves. He is the youngest to reach the mark at 29 (Francisco Rodriguez was 31) and has needed the fewest games, 494 (Mariano Rivera had done so in 537 games) and save opportunities (330, compared to 335 for Joe Nathan) to do so.

On May 5, 2018 — In pitching a perfect 9th inning in a 6 – 5 win against the Rangers, Craig Kimbrel of the Red Sox becomes the 29th man to record 300 saves. He is the youngest to reach the mark at 29 (Francisco Rodriguez was 31) and has needed the fewest games, 494 (Mariano Rivera had done so in 537 games) and save opportunities (330, compared to 335 for Joe Nathan) to do so.

Source:
Baseball Reference May 5