Bangladesh opener Shadman Islam smashed a century in the second Test against Zimbabwe on Tuesday, giving the hosts a lead of 64 runs at the end of the second day with three wickets in hand. Bangladesh were 291-7 at the close, with Mehidy Hasan Miraz (16) and Taijul Islam (5) remaining not out, in response to Zimbabwe's first innings total of 227.  Shadman recorded a career-best knock of 120 and partnered with Anamul Haque in a first-wicket stand of 118 runs, only the 10th time that Bangladesh's openers had passed the 100-run mark in Tests.  Despite Shadman's century, the other batsmen failed to exploit the dry and slow surface at Chattogram after a good start.