Pakistan opener Mohammad Rizwan's recovery from a lung infection to make a valiant innings in the Twenty20 World Cup semi-final was termed "miraculous" on Saturday by the Indian doctor who treated him.

Rizwan, 29, came out of the intensive care unit of a Dubai hospital to top-score with 67 in Pakistan's 176-4 on Thursday, but his efforts were in vain as Australia overhauled that total to set up a title clash with New Zealand.

Rizwan's courage was lauded by Pakistan's batting coach Matthew Hayden and by fans, while pictures of the batsman lying in a hospital bed went viral on social media.

Saheer Sainalabdeen, a pulmonologist who hails from the south Indian state of Kerala, told AFP it was Rizwan's "faith in God" and desire to play for Pakistan that got the batsman through a severe chest infection.

Rizwan was so grateful that he sent the doctor an autographed Pakistan shirt.

"I must admit that we did not expect his recovery to be so fast as it takes around five to seven days for improvement with the kind of condition that he came in with," Sainalabdeen told AFP.

"But because of his fit lifestyle, of course he is a sportsperson, he improved in two to three days and it was miraculous.

"Main thing I thought was his faith in God and his strong belief to play in the World Cup for his country."

Sainalabdeen said Rizwan was admitted to the hospital on November 9 with severe chest pain and doctors suspected heart issues but later it turned out to be spasm of the lungs and food pipe.

"It all started with cough and cold but November 9 he had severe chest pain and we had a doubt of him having heart issues," he said.

"But then the evaluation found out that he had severe throat infection which led to spasm of the lungs and food pipe. Because of which he had severe pain and breathing difficulty."

Once Rizwan was passed fit, he tore into the Australian bowling in Thursday's semi-final, taking nine balls to get going with skipper Babar Azam as he hit Josh Hazlewood for six. 

The batsman smashed three fours and four sixes in a 52-ball blitz before his dismissal in the 18th over. He jumped to second in the tournament's batting chart with 281 runs in six matches, behind only Babar's 303 runs. 

Sainalabdeen, who works at the Medeor hospital which helps assure the bio bubble at this World Cup, said he felt "good" watching Rizwan's knock on TV.

Rizwan, a wicketkeeper-batsman who hails from Peshawar, has played 49 T20 matches for Pakistan, scoring 1346 runs at an average of over 51 since his debut in 2015.