Interim Bangladesh head Courtney Walsh dragged away 12th man Nurul Hasan who engaged in a verbal clash with Sri Lankan opener Kusal Mendis -- who was being restrained by Tamim Iqbal -- after Mahmudullah Riyad struck a deep six over the square leg region to clinch a scintillating two-wicket win that knocked Sri Lanka out of the Nidahas Trophy and powered Bangladesh to the final at the R Premadasa Stadium in Colombo yesterday.

Off-field incidents such as returning captain Shakib Al Hasan urging Mahmudllah and Rubel Hossain to come off the field in protest, after the leg umpire had called a no-ball following a second over-the-shoulder ball from Isuru Udana in the third ball of the last over only to rescind his decision moments later, took some of the sheen off a spectacular game.

That decision led to things getting heated. Nurul Hasan entered the pitch with some drinks and found himself embroiled in a heated exchange with Sri Lankans just before Shakib's outburst and the game was stopped for 10 minutes before Bangladesh team manager Khaled Mahmud asked his players to continue.

When the game finally resumed after the chaotic scenes, Bangladesh required 12 runs from four balls and Mahmudullah returned to face Udana.

The right-hander impressively refocused and struck a four towards widish extra cover, before taking a double off the next ball and finally ending things with a six to remain unbeaten on a match-winning 18-ball 43 and register a memorable win.

Bangladesh will take on India in the final of the tournament tomorrow.

Going back to the controversial decision, with Bangladesh requiring 12 runs off the last over, Udana bowled a short ball to Mustafizur that yielded no run and the umpire signalled it as the first bouncer of the over.

Udana once again bowled a short delivery in the next ball which Mustafizur failed to connect with before running off for a single. He was run out at the bowler's end, following which Mahmudllah walked over to the leg umpire and queried whether it was a no-ball as it was the second bouncer of the over. Although later denying it, at one point the leg umpire Raveendra Wimalasiri did seem to signal for a no-ball.

Nurul, the 12th man, was then engaged in a clash with Sri Lankan fielders and was dragged back towards the dugout as emotions ran high between both sets of players.

In chase of 160, Bangladesh struggled to get started as they fell to 33 for two after losing Liton Das (0) and Sabbir Rahman (13), who was promoted to number three, inside four overs. Tamim Iqbal and Mushfiqur Rahim then steadied the ship and played sensibly to take the Tigers to 50 runs in the Powerplay.

The pair added 64 for the third wicket, but stumbled again as Mushfiqur was caught at extra over off the bowling of Amila Aponso after scoring a 25-ball 28. Tamim departed after 43 balls, coming down the track after reaching his half-century and edging to the keeper.

Shakib then joined Mahmudullah with Bangladesh requiring 50 off the last five overs and the duo played sensibly to bring the equation down to 27 runs required off the last three overs.

However, Shakib departed after scoring seven off nine, handing a straightforward catch to Akila Dananjaya at deep fine leg after going for a flick to Udana. The fielder celebrated the catch by imitating a snake charmer playing his flute; a fitting rebuttal to Bangladesh's Nagin Dance.

The game went down to the wire, Bangladesh needing 23 off the last 12 balls. The Tigers then plundered 11 off the penultimate over bowled by Thisara Perera before the drama unfolded.

Earlier, Shakib, who replaced Abu Hider in the playing eleven, opted to field and the Tigers' initial brilliance with the ball reduced Sri Lanka to 41 for five inside nine overs.

But Shakib opting for the unusual theory of not bowling a left-arm spinner against left-handers Kusal Perera and Thisara Perera, changed the course of the game as the pair added 97 off 61 balls for the sixth wicket.

Kusal struck his 10th T20I fifty and completed 1,000 runs in the shortest format of the game before eventually departing for 61 off 40 balls in the 19th over. Thisara also blazed his way to a fifty before being dismissed off the last over as Sri Lanka pillaged 60 runs off the last five overs to post 159 for seven in 20 overs.