The captain brings on his offspinner when a left-hander comes to the crease. Happens all the time, of course. Nathan Lyon was always going to be a key bowler for Australia in Chittagong, with five left-handers among Bangladesh's eight specialist batsmen, but he probably didn't expect all five to occupy the top five positions.
It certainly played some part in the rhythm he got into over the course of his first two spells of nine overs each, and he cleaned up the top order while becoming the first bowler to take the first four wickets in a Test match with the lbw mode of dismissal.
Tamim Iqbal was initially troubled by Pat Cummins before Lyon got him to miss a forward defensive to a ball that was quicker through the air. Imrul Kayes fell attempting a cross-batted release shot off just the 11th ball he faced, and it was disappointing to see him bring out his Hail Mary so early in the piece. Soumya Sarkar worked hard throughout the first session, keeping Lyon at bay for 44 deliveries before missing a straight one two balls before lunch.
Mominul Haque, who looked to be getting set after experiencing a whirlwind two weeks since being dropped from the Test team and then reinstated, got out looking to work one across the line. There was no spin, and Lyon's cunning change of pace did the rest.
Lyon's general idea was to bowl straight, aiming at the pads and hoping for the batsmen to miss, and in doing so exposed the Bangladesh left-handers' frailties against plain old offspin. There was a lack of on and off-field planning in their approach, hesitant footwork, and a tendency to wait for things to happen.
In the past 12 months, they have struggled against similar offspinners who bank on line, length, subtle changes of pace and natural variation rather than mystery.
Left-handers accounted for eight of Moeen Ali's 11 wickets in Bangladesh last year, and six out of Dilruwan Perera's eight wickets in Sri Lanka earlier this year. R Ashwin's six wickets in the Hyderabad Test included those of four left-handers. Lyon, so far, has taken 14 wickets in this series, of which nine have been of left-handers.
Having got through the physical challenge of bowling 28 overs on a hot day, Lyon said he had managed to bowl four straight ones, all getting him wickets.
Two things stood out in particular as Lyon kept hitting the left-handers' pads. Firstly, the batsmen looked like they didn't really have a well-crafted plan against his offspin, and seemed not to have learned any lessons from their struggles against Moeen, Ashwin and Perera. The majority of them seemed to be playing Lyon off the pitch.
Secondly, the team management didn't try to break up the line of left-handers in their top order by promoting Mushfiqur Rahim, Sabbir Rahman or Nasir Hossain. Doing so could have forced Lyon to think differently, or at least strive a little harder to maintain his lines.
Left-handers accounted for eight of Moeen Ali's 11 wickets in Bangladesh last year, and six out of Dilruwan Perera's eight wickets in Sri Lanka earlier this year. R Ashwin's six wickets in the Hyderabad Test included those of four left-handers. Lyon, so far, has taken 14 wickets in this series, of which nine have been of left-handers
Bangladesh have picked Sabbir and Nasir as quick run-getters, and may have thought it risky to promote either of them. They are, however, in the team as specialist batsmen and should be prepared to bat anywhere in the top six. The other argument against promoting a right-hander or two could have been that Tamim, Soumya, Imrul and Mominul are predominantly top-order batsmen, and that shuffling their positions around may not have done them much good. But moving one of them - perhaps Mominul - down the order to let Mushfiqur take on Lyon could have been a prudent idea.
Mushfiqur has been floating around the batting order in the last one year, so he was possibly the best equipped among the middle-order batsmen to tackle a change in position and counter Lyon. By the time he faced him, Lyon had bowled 15.4 overs.
Mushfiqur and Sabbir added 105 runs for the sixth wicket, taking different approaches against Lyon. Mushfiqur was solid, hardly taking chances and only scoring 13 off 39 balls against him. Sabbir ended up with a strike rate of 110.52 against Lyon, hitting him for two fours and a six. He eventually fell to a poor ball from Lyon, but by then had shown the top five a possible approach they could take against Australia's main bowler.
Lyon will continue to be in the thick of things as Australia try to push towards a drawn Test series. Tackling him in the third innings will be Bangladesh's last chance to show they have plans for him. A change in the batting order could help, with the solid Mushfiqur possibly moving up to No 4 and displacing a left-hander to No. 6. But with a Test series win on the line, will the team management go for a move that risks destabilising the batting line-up? Perhaps a more proactive approach from the five left-handers could do the trick.
Mohammad Isam is ESPNcricinfo's Bangladesh correspondent. @isam84