Pakistan team doctor Najeeb Somroo later revealed Rizwan had spent two days in a hospital intensive care unit due to a chest infection.
"Mohammad Rizwan developed a severe chest infection on November 9th after which he was admitted to the hospital. He spent two nights in the ICU recovering," Somroo said.
"He made an incredible recovery and was deemed fit before the match. We can see his great determination and tenacity that shows his spirit of performing for the country. And we can see how he performed today."
He added: "The decision regarding his health was made by the whole team management. This was regarding the morale of the whole team and therefore we kept it within the team."
Pakistan captain Babar Azam, who made 39 to lead the tournament's batting chart with 303 runs, praised his opening partner's "exceptional" attitude.
"Definitely he's a team man. The way he played today, it was exceptional," Babar said.
"When I saw him, he was a little bit down, but when I asked him about his health he said, 'No, I will play'. And the way he played today he showed that he's a team man. And I am very confident about his attitude and his performance."
During Friday's semi-final, Rizwan became the first cricketer to accumulate 1000 T20 international runs in a calendar year.
In 2021, he has scored 1003 runs in 20 T20I innings at an average of 86.08.