When Saifuddin came on to bowl the 44th over for Bangladesh, Sri Lanka needed 53 from 42 balls with set batter Wanindu Hasaranga batting on 70 from 56 balls.
Five deliveries and six runs later, in the last ball of the over, Saifuddin had Hasaranga's wicket.
It was a length ball outside off which Hasaranga pulled but couldn't control, and the catch was taken safely by Afif Hossain at deep mid-wicket.
It was a tired shot but one that was coming as Saifuddin had bowled the over with controlled deliveries outside off and on the middle stump and kept things tight and simple.
It was the turning point in the match and helped Bangladesh win the match by 33 runs.
In a pre-match press conference, the all-rounder revealed how he took the wicket.
"I have played against Hasaranga in the Under-19 World Cup. I know a bit about him from there and he batted well. I'm happy to have been able to bowl according to the field we set up for him and get his wicket," he said.
The extreme heat has been a point of discussion in the match and the players have had to work harder than usual and Saifuffin explained that they tried to stay as hydrated as possible.
"We had a practice match at BKSP and that helped us get an idea of how to play in these conditions. Drinking water in between overs and staying hydrated was important," he added.
Saifuddin also explained that he worked hard in the month or Ramadan to get back in contention for the team's starting XI after not being a regular in the last few series.
"I worked really hard during Ramadan and I had a fire in me to play from the first match. That's the promise I made to myself when I was leaving my home to join the team. Thankfully I've been able to play in the first match and show what I can do," he explained.
Mohammad Mithun has been struggling at number five and Saifuddin says he'd "prefer to bat at number five or six" but he know that it won't be possible given the team combination.
He's however hopeful that down the line he can show more with the bat and get a promotion up the order.
Bangladesh lead the ODI series 1-0 and play the second match on Tuesday in Mirpur.