Mustafizur Rahman has been treated as Bangladesh's most important bowler for the last three years. He bowls a few overs with the new ball, then comes back for a few more after the 30th over, and then bowls the rest in the last five overs. Mashrafe Mortaza has always ensured that Shakib Al Hasan, the best bowler at his disposal, gets to bowl when Mustafizur is not in the attack. So, on Wednesday, it was a major challenge for both Mustafizur and his captain in a crunch Asia Cup match against Pakistan. Mashrafe was leading without Shakib in the Bangladesh line-up for the first time in three years. And how well did the two respond.

There had to be a moment when Mustafizur would rise above the rest to show what makes him a special bowler, and not just a freak of nature. With his four-wicket haul, he stepped up on a day when the bowling attack was without Shakib. When Shakib eventually returns, Mustafizur wouldn't have to think about such responsibilities, but Abu Dhabi must have been a journey into self-discovery for him. That he is capable of leading a bowling attack with more experienced bowlers around him. That he can deliver under the pressure of expectation, in and out of the dressing room. It has been a trait missing in most of Bangladesh's young cricketers for a considerable period now.

Without Tamim Iqbal in this tournament, the openers have failed repeatedly. Three early wickets on Wednesday meant that Mushfiqur Rahim, Mohammad Mithun and Mahmudullah had to curtail their aggressive approach. They couldn't attack freely, nor were they able to consolidate for too long, because a total under 200 would have been far less severe on Pakistan.

But it was going to be tricky to defend 239 runs without Shakib. Most batting line-ups deal with him conservatively, so when he is not around, it gives them ten overs to score with relatively more freedom. In fact, this was the first time in four years that Bangladesh were playing without a left-arm spinner, so they were well and truly out of their comfort zone.

After Mehidy Hasan struck early, Mustafizur began by attacking the stumps and building up pressure through disciplined bowling. Babar Azam and Sarfraz Ahmed, too, fell early as a result of that, and Pakistan were 18 for 3.

Mahmudullah then lessened Mashrafe's burden by bowling smartly in three spells of two, six and two overs. Just after Mashrafe had taken a stunning catch off Shoaib Malik's flick, Mahmudullah tied down Shadab Khan for 11 deliveries that took the sting out of Pakistan.

Captains often call it luck, but Mashrafe is at times so good at his man-management skills that people respond differently to him. Mahmudullah, who bowled his full quota for the first time in four years, combined with Mehidy to take 3 for 66 from their 20 overs, while Soumya surprised with his 1 from 19 from five overs.

It is hard to replace Shakib's accuracy and wily changes of pace, and it will probably take a long time to find another bowler like him. He is economical in any situation, and is Bangladesh's highest wicket-taker in the middle overs in the last three years. He is also a dot-ball gatherer in the last Powerplay. But then, there is Mustafizur.

Mustafizur's skill-set is well-known for the cutters and slower balls, but after recovering from his shoulder and back injuries, Mustafizur has worked hard to regain his pace, the type that generates a good bouncer and can often take the ball away from swinging bats in the end overs.

Pakistan's lower order was no match for Mustafizur, who kept mixing it up. He bowls well away from the body and then pins batsmen at the crease, without offering much room to maneouver the ball. It is actually quite wonderful to see that even someone as freakishly talented as Mustafizur has learned particular deliveries just so that he can be effective at certain points in a game. Heath Streak and Courtney Walsh can be proud of their ward.

But it is also hard to forget who and what led Bangladesh through these turbulent two weeks. Mashrafe doesn't let pressure get to his relatively young team, and he does everything he can to ensure that they remain as insulated as possible. He is regarded as a father-figure to many of the players, but the true measure of his leadership skills would always come in these matches, when Bangladesh face the toughest of circumstances. A bowler like Mustafizur certainly helps, too, particularly when he offers control.

Mashrafe has injected self-belief in the players in the last three years. It has worked with some of them, and not with others. But in tight games, when players are asked to dig deep, they know very well that their bhai wouldn't be impressed with anything less than full commitment to the cause, the very least they can do for a team without their two best players.

Mohammad Isam is ESPNcricinfo's Bangladesh correspondent. @isam84