Yes, I think they can, Sri Lanka is not the strongest team like they were the last time, I am hoping for an upset and the odds for Afghanis are too good to not bet. Infact the odds are going downwards as many people realize that Afghanis might have a chance.
Not even in their wildest dream they can beat Sri Lankans.Sri Lanka is one of the best teams in T20 ,Afghan fairly qualifies for it.The odds are still in the favor of Sri Lanka.Check the link I posted two comments above.You're making a mistake by falling for good odds ,bet on most sixes ,that would obviously be Sri Lanka @ 1.86.
Afghanistan win the toss and elect to bat first because this pitch going to slow down later on. Don't underestimate this Afghanistan team, they are quite good but only they need to improve on batting side. If they add more than 150 runs in this match, they can defend that score because they bowling and fielding is quite good.