Tamminen has been in goal for each of the team's three clean sheets across all competitions this season, with all of them coming during Tanya Oxtoby's tenure. However, her most recent appeared to be the one that's brought her the most joy.
It was a tough start to life as a United player for Tamminen and injury meant she didn't make her debut until the Tyne-Wear derby at St. James’ Park in November.
But her penalty save in that game, and subsequent impressive performances, have quickly endeared her to the Magpies supporters, and Sunday was another shut-out for the Newcastle netminder.
"I am so relieved and happy to get a clean sheet," Tamminen said post-match. "But I'm also happy to see us score a second goal and kill off the game, because I thought our performance deserved that at the end.
"The conditions were quite difficult, so I can't really say that I enjoyed how we played, but I did love to see how hard everyone worked throughout the game and showed our great work ethic.
"I think you could see that in the way we defended our goal, people were making blocks and throwing bodies in front of the ball to get a clean sheet."
It was all the more important for Newcastle to pick up three points against Pompey as it's now three weeks until their next match.
They made it back-to-back wins for the second time under Oxtoby, and United are showing signs of finding the consistency required for the back end of what has been a tight WSL2 season.
"This was a very important win for us heading into our break," Tamminen acknowledged. "We'll have players going away on international duty soon, so this win was needed for us, mentally, to ensure we're all in a good place.
"I also had my family over for the game as well as some friends from Sweden, so to get a win in front of them and all of our amazing fans here at home was such a great feeling."
An injury to Deanna Cooper, who has not played since the reverse fixture against Portsmouth in December, has seen a defensive reshuffle in recent weeks with summer signing Jemma Purfield slotting in at centre back alongside Aoife Mannion.
"Of course, I take a lot of pride in keeping clean sheets, but it's not just me; this is a shared achievement," added Tamminen. "Our chemistry as a defence is getting better with every game.
"When Deanna got injured and Jemma came in, it took some time to get to know each other and understand how we all like to play, but now it all feels natural and is going well."
