Pakistan bowling coach Morne Morkel on Wednesday said injuries to their premier quicks is a big blow ahead of a must-win Asia Cup match but a "fantastic opportunity" for up-and-coming talent.

Naseem Shah has been ruled out of the team's final Super Four match -- effective semi-final -- against Sri Lanka in Colombo on Thursday, with Pakistan Super League star Zaman Khan coming in as replacement.

Naseem and fellow quick Haris Rauf were injured in the team's previous Super Four clash of the 50-over tournament, a prelude to the upcoming ODI World Cup.

"A big blow, picking up those little niggles, but in this same sort of thing what a fantastic opportunity for the guys coming in," Morkel told reporters.

"After going down against India, it's a must-win game for us come tomorrow and I'm quite excited to see the new guys stepping in, to see their character, to see how they respond."

Zaman flew in from Pakistan and is already a popular name in national cricket after his heroics in this year's PSL for champions Lahore Qalandars.

The 22-year-old is expected to make his ODI debut in a high-pressure match.

"I'm excited just to work with him, connect with them and build that relationship and help him develop, because he's a match winner," Morkel said of the quick who won defended 13 runs of his last over to star in Lahore's title defense this season.

Shaheen Shah Afridi leads the Pakistan pace attack that rattled India in the Asia Cup group match, which was washed out after just innings.

But Shaheen and company took a hammering in their last meeting with India, who posted 356-2 in a match played across two days due to rain.

Morkel said the 228-run loss to India has been good learning ahead of the 50-over showpiece event where they will meet the arch-rivals on October 14.

"Those are fantastic learnings for us," said Morkel, who rated Shaheen as "world-class".

"The more tough situations we can face leading into the World Cup, that's brilliant. You know, we're gonna grow from this and then come back stronger."

Critics have pointed at Pakistan's lack of quality spinners, a major drawback on turning Sri Lankan wickets, but Morkel insists the slow bowlers remain ready to perform.

The former South African fast bowler, who played 86 Tests, 117 ODIs and 44 T20 matches for his 544 international wickets, has been seen bowling to the Pakistan batsmen in the nets.

Rain could once again play spoilsport in Colombo today, with 93 percent chances of rain during the day and 48 percent during the night, as per Accuweather. Pakistan, however, will hope for the match to be completed as even a sharing of points will see Sri Lanka go through due to superior net run-rate.