Shaheen Shah Afridi warned he is still not back to his fearsome best even after leading Pakistan into the Twenty20 World Cup semi-finals with figures of 4-22 against Bangladesh on Sunday.

The left-arm frontline fast bowler rattled the opposition batsmen with his swing and seam in Adelaide to limit Bangladesh to 127-8 as Pakistan won the do-or-die clash by five wickets.

The 22-year-old missed the recent Asia Cup with a knee injury and is still working his way back to full fitness after being out of action for three months.

"It is not easy to come back from such an injury," Shaheen said.

"I can only give my 100 percent on the field, and I am trying. This injury needed time, I think I came (back) early as it is a World Cup and the team needs me."

Shaheen struggled for wickets early in the tournament as Pakistan suffered losses to India and then Zimbabwe in Group 2.

But he seemed to have found rhythm in a win over the Netherlands and came into his own with a match-winning 3-14 against South Africa, a victory that revived their campaign.

Pakistan's last Super 12 match turned out to be a virtual quarter-final after the Netherlands stunned South Africa in the earlier game.

Shaheen rose to the challenge after Bangladesh elected to bat first and sent back Liton Das for 10 in the third over.

It was his double strike in the 17th over that broke Bangladesh's back and he took one more to bag four wickets for the first time in T20 internationals.

"I am not bowling at 150 kph like Haris (Rauf)," Shaheen said.

"Even before I bowled at 135-140 kph. (Earlier) I felt a pinch during run-up but now feeling much better.

"Staying in the room for two-three months with an injury affects your mind."

He added: "I believed that I would come back and my efforts would pay dividends."

It has not been the best of tournaments for star batsman and skipper Babar Azam, who made a laboured 25 off 33 balls after scores of 0, four, four and six.

But Shaheen praised the team's comeback and the captain for his support.

"The credit goes to the whole team. We played good cricket. The games we lost were decided on the last ball, but still we played good cricket," said Shaheen.

"We didn't get the results in our favour but a good team never falls after a loss.

"The captain plays a big role to lift the team and support us. We are backing each other and as a result we have won here."