Sri Lanka cricketer Kusal Mendis plays a shot during the first Twenty20 cricket match between Bangladesh and Sri Lanka at the Sher-e-Bangla National Cricket Stadium in Dhaka on February 15, 2018. Pic/AFP

Opener Kusal Mendis scored his maiden half century in Twenty20 internationals to lead Sri Lanka's six-wicket rout of Bangladesh in the first of the two matches in Dhaka on Thursday.